Internet E-Mail Workshop/Internet E-Mail Workshop.iso/info/audio393.

Text File | 1993-11-24 | 175KB | 3,732 lines

·    Subject: rec.audio FAQ (part 1 of 4)

Archive-name: AudioFAQ/part1
Last-modified: 1993/3/2
Version: 1.2

1.0 Contents:

    Part 1:
    1.0    Contents
    2.0    Organization
    3.0    Purpose
    4.0    Omissions
    5.0    Credits
    6.0    Errors and Corrections
    7.0    Disclaimer
    8.0    Copyright Notice
    9.0    Speakers
    10.0    Amplifiers
    Part 2:
    10.10    Amplifiers (continued)
    11.0    CD Players, CDs, Turntables, and LPs
    12.0    High Fidelity Systems
    Part 3:
    12.4    High Fidelity Systems (continued)
    13.0    Listening Rooms and Houses
    14.0    Recording
    15.0    Mail Order
    16.0    Wire
    Part 4:
    16.4    Wire (continued)
    17.0    The Press
    18.0    Retail
    19.0    Miscellaneous
    20.0    Net Protocol

2.0 Organization:

This FAQ is divided into a preamble and a list of subjects.  Each
subject is described by a list of questions and answers.  Some
questions have no answers yet.  That's life.

This FAQ is split into four individual postings.  This FAQ also
references a frequent posting of sources for audio via Mail Order.
That list is maintained by [e-mail] (William R. Nau).  Contact
Mr. Nau directly for information or corrections to that posting.
The list is also available via FTP in the pub/rec.audio directory
of SSESCO.com.

Lines beginning with "|" are new since the last version of the FAQ.

3.0 Purpose:

The purpose of this FAQ is to address frequently-asked questions as
a whole, so that rec.audio volume can be reduced.  Towards this end,
we assembled a list of common questions, and some general answers to
these questions.  Audio is part science and part art, so some of the
answers are objectively correct, while others try to open-mindedly
present both sides of a subject.

4.0 Omissions:

Many valuable things have been left out of the FAQ.  In part this is
because there is just too much to say about audio.  In part, this is
because the general reader doesn't need that much detail.  Also, some
things were omitted because they are too controversial or inflammatory.

5.0 Credits:

This FAQ is the work of many people.  Allow me to thank everyone who
helped now.  We appreciate all of your contributions.  However, all
blame and criticism should go to Bob Neidorff at [e-mail].
Some of the contributors to this FAQ are listed below.  Others have
made great contributions, but are no less appreciated.

    [e-mail] (Andrew Hume)
    [e-mail] (jj)
    [e-mail] (Bob Neidorff)
    Rick Oakley (no internet access)
    [e-mail] (Richard d Pierce)
    [e-mail] (Paul Smee)
    [e-mail] (Gabe M. Wiener)

6.0 Errors and Corrections:

Some errors are intentionally included in this FAQ.  (It's easier to say
that and later admit we were wrong, than to claim that this is a best
effort).  If you have a correction to the FAQ, additional information,
or a new topic for the FAQ, please send e-mail to [e-mail]
describing your thoughts in detail.  Please include your e-mail address
in your submission, so that we can stay in touch.  Every submission will
be considered for inclusion in the next release of the FAQ.  This FAQ
will be reposted every two months.

7.0 Disclaimer:

Everyone's human.  Nothing is perfect.  The people who wrote the
information here put varying amounts of research into their work.
To the best of my knowledge, no one made any contribution or
comment because of a vested interest.

Audio is a very lucrative and competitive industry, filled with
honest companies, aggressive marketing people, people who stretch the
truth very thin, excellent products, and lousy products.  We tried
hard to screen the hype from valuable data.  If we insulted, omitted,
or otherwise disturbed you, your company, your product, or something
you feel strongly about, please let me know.

The information here attempts to paraphrase a large portion of the
information exchanged on rec.audio.  At times, people will make
recommendations or suggestions to others on rec.audio.  Some of these
statements are included here because we have been asked to include
statements of that sort.  These statements, and everything in this
document is the opinions of various people.  Nothing here is intended
as recommendation or suggestion.

Further, no matter how it is worded, nothing here should be taken as
fact.  The authors take no responsibility for any use of this
information.

8.0 Copyright Notice:

The information contained here is collectively copyrighted by the
authors.  The right to reproduce this is hereby given, provided it is
copied intact, with the text of sections 1 through 8, inclusive.
However, the authors explicitly prohibit selling this document, any
of its parts, or any document which contains parts of this document.

9.0 Speakers:

9.1 What should I listen to when evaluating speakers?
    The most important thing is to listen to recordings that
    you *know*.  Any good salesman will play you recordings
    that highlight that particular speaker.  Do not be embarrassed
    about bringing a stack of CD's with you to the hi-fi shop.

    Do not spend your valuable listening time switching between a
    dozen pairs every 3 seconds.  If you are shopping at a quality
    store, the dealer will, from the description of your room, your
    size requirements, your musical tastes, and your budget, be able
    to show you a couple of pairs that will be close to what you
    want.  Spend several minutes listening to each.  When you think
    you're close, don't be embarrassed about spending half an hour
    or more listening to the speakers.  You're going to have them in
    your home for a lot longer, and many speakers will cause
    "listening fatigue" after a short time.  Make sure you really
    like them before you hand over money.

    One thing to try is well recorded "Spoken Word" records; most
    people have a very good ability to tell when a speaking voice
    sounds unnatural, even if they've never heard the person
    speaking live.  If you play an acoustic instrument, find
    something that features that instrument solo, or in a small
    group; make sure it really sounds like it should.  Almost
    everyone has heard a live piano.  Piano can be very revealing.

    Blues, jazz, folk, or 'easy listening' music with simple
    instruments and a female vocalist is also revealing.  Well done
    female singing voices provide a very good test of a system's
    response.  Try something simple and soft, which will let you
    hear any noises coming from the system; and something complex,
    with lots of instruments all happening at once, to make sure the
    system doesn't go muddy when things get complicated.  And, of
    course, try a few of your favorites, and see if you like what
    happens with them.

    If a sales person suggests some music to listen to, the odds are
    that it isn't the most revealing.  Sales people tend to suggest
    things which sound great.  Anything you own and like is good,
    because you know it and are happy to listen to it carefully.  No
    matter how good the recording, if you don't like Opera, you
    won't listen to it as carefully as your favorite, scratchy,
    1940's rhythm and blues.

    Most important is to listen to something you are familiar with.
    Even if a recording is flawed (and what ones aren't?), how is it
    different from your normal setup?  Some of the most important
    differences are "Gee, I never heard that instrument before!"

9.2 What should I listen for when evaluating speakers?
    When comparing two speakers side-by-side, doing an AB
    comparison, be extremely careful to match the levels before
    evaluating.  A slight level difference can make one speaker
    sound better, even though the difference may not be perceived
    as a level difference.  Some claim that you will be influenced
    by a difference of less than 1/2 dB!

    First and foremost, the sound should be natural.  If you listen
    to vocals, close your eyes and try to picture someone singing in
    the same room with you.  Does it sound realistic?  Likewise with
    instruments.  You selected recordings of instruments that you
    like and have heard live.  Do they sound like what you remember

    them sounding like live?

    Your very first impression should be something like "what nice
    sound".  If your initial gut reaction is "gosh, what a lot of
    detail", the system is likely to be heavy in the treble (often
    interpreted by beginners as "more detailed") and you'll probably
    find that annoying after a while.  If your first reaction is
    "hey, what powerful bass", then the system is probably
    bass-heavy, rather than ideal.  The most common mistake for
    beginners is to buy a system with REALLY powerful bass, because
    it sounds "impressive" at first.  After a while, though, you'll
    get tired of being thumped on the head by your music.

    Not to say that good bass and treble aren't important.  But your
    first realization should be that the music is all there, and
    that it comes together as good music, without one particular
    part trying to dominate it.  Sit back and listen to it for a
    bit.  You should be able to pick out the individual instruments
    if you want.  They shouldn't force themselves on you, and you
    should also be able to hear the music as a single piece, the sum
    of its parts, without feeling like each of the instruments is
    trying to grab your attention away from the others.

    You should check how things sound with the amp turned up, and
    also with it turned down to a fairly low volume level.  Some
    speakers which sound very nice at low levels begin to sound
    confused, like they can't cope, when turned up.  On the other
    hand, some sound nice loud, but sound thin and bodiless when you
    turn them down a bit.  With the spoken word or female vocalist,
    listen for "sibilance", a pronounced 'hiss' at the end of 's'
    and 'z' sounds.  It shouldn't be there.  Most planar speakers
    just can't play very loud.  Whatever you hear, do some
    auditioning at the maximum volume you anticpate ever wanting.

    It is acceptable and sometimes desirable to switch the stereo to
    mono to evaluate naturalness.  Mono is a good test of both the
    room and the speakers.  The image should be rock-solid dead
    center, and not move with signal or level.  If it isn't perfect
    mono, it will be nearly impossible to create a good stereo.

    A speaker in a large box is capable of producing low frequencies
    at higher volumes with more efficiency than a small box, but
    that doesn't mean that a small box can't have great bass, it
    just won't be as efficient and can't play as loud.

    Good speakers can "recreate a natural stereo sound stage",
    placing some instruments to the left of the left speaker, some
    sounds in the middle, and some to the right of the right
    speaker.  Poorer speakers make it harder to localize voices.

9.3 Why use a subwoofer?  Will it help?  One or two?
    One reason to get a subwoofer is to add bass to a feeble system.
    A second reason is to move the lowest frequencies to a separate
    driver, and thereby reduce a particular kind of distortion
    caused by the nonlinear mixing of different sounds, called
    "intermodulation distortion". A third is to increase the power
    handling ability of the system and the overall reliability.  All
    are valid reasons, but it isn't so simple.

    To improve the sound of a good speaker system, a subwoofer must
    "integrate smoothly" into the system, extending the bass without
    causing peaks or dips.  Many subwoofers have a crossover that
    goes between your amp and your main speaker which sends the lows
    to the subwoofer and sends the higher frequency signals to the
    main speakers.  This may damage the perfect sound of a good
    system, it may sound similar, or it may sound better.

    Most good small speaker systems have a bass peak at resonance,
    which attempts to compensate for the absence of lower bass.
    Like it or not, this is the only way to make a small system
    sound realistic. If the small system is done well, the
    improvement you will get from a subwoofer will be small, but
    still real and, to many, significant.

    Correctly done, a good subwoofer will enhance the sound of a
    good small-box system.  Done wrong or haphazardly, anything is
    possible.  Even a fine large speaker system might benefit from
    careful addition of a subwoofer.  However, the better the
    original system, the more likely it will be that a modest
    subwoofer will do more harm than good.

    Low frequencies travel less directionally than high frequencies,
    so many people say that only one subwoofer is required for good
    sound.  This is true to some extent, but not completely true.

    There are a few reasons for getting two subwoofers.  Some feel
    that you need two subwoofers to accurately reproduce the stereo
    image, no matter how little low-frequency stereo information
    there is.  Others feel that two subwoofers are much easier to
    set up in a room, less likely to excite standing waves in the
    room, and give smoother sound.

    A third reason is that two subwoofers can produce twice the
    sound of one.  Finally, even though subwoofers produce very low
    frequency sound and very low frequency sound is non-directional,
    subwoofers also have output at 100 Hz, and sound at 100 Hz is
    directional, so two subwoofers will give a slightly better
    stereo image than one.  Assuming, of course, that the two are
    separated by at least two feet.

    Finally, even though original source signals rarely contain any
    music with stereo components below 50Hz, there may be some noise
    component with low-frequency out-of-phase noise.  This unusual
    noise might add a sense of space to a recording if it is
    reproduced by a system in which the woofers are very far apart.

    It is still true that a single good subwoofer, correctly added
    to a system will help the sound but two will probably help more.

9.4 How do you connect a subwoofer to a stereo?
    Many subwoofers contain their own amplifier and crossover.
    For these, take the preamp output and feed it into the subwoofer
    amp input and also into the main amplifier.

    For other subwoofers, just run them in parallel with your main
    speakers, or combine them into your system with your own bass
    amplifier and crossover.

    Some A/V receivers contain a splitter specifically for use with
    subwoofers.  If you have one of these, you will either want a
    separate amplifier for your subwoofer or an amplified subwoofer.

    Consult the manual which comes with the subwoofer.

9.5 What do I need for surround sound?
    "Surround Sound" has referred to a number of different products
    over the years.  Many mass-fi receivers have "Surround Sound"
    buttons that do little more than muck up the imaging.

    In recent years the term "Surround Sound" has become synonymous
    with the surround systems produced by Dolby Laboratories.  Dolby
    Surround comes in several flavors, such as passive surround
    (which simply decodes the phase information and sends it to the
    rear speakers) and the more advanced system called Pro Logic.
    Pro Logic system uses computer circuitry to route directional
    information to the appropriate speakers.

    Generally, one needs at least two more speakers beyone the main
    stereo pair.  Advanced Pro Logic systems such as the Lexicon and
    Fosgate can accommodate several more speakers beyond the two
    additional ones (usually placed in the rear).  Often one can
    find Pro Logic systems with two front, two rear, two side, as
    well as a center channel speaker for dialogue.

9.6 I was just approached (accosted?) by a couple of kids driving a van
    that said they had some GREAT speakers to sell. They are
    overstocks, used by major recording studios and DJ's or even
    hot, and they normally sell for $1000/pr, but they'll let me
    have them for just $399. Am I getting ripped off?

    Yes, you most certainly are. The speakers these people sell are
    none of what they describe. They are never used in studios.
    There might be one or two DJ's out there that use them because
    they can't afford anything else.  They are not overstocks, and
    in all likelyhood, they are NOT HOT!.

    Are they good speakers? No, they're, at best, no better than the
    big boom boxes you find in $400 rack systems in department
    stores.  They are worth no more than what the kids paid for them
    ($100/pr).

    The speakers go under names like "Acoustic Monitor DB IV",
    "Acoustic Linear," "Pro-Poly," "Audio Reference 4350" and so on.
    They all "feature" things like "liquid cooled 3" tweeter",
    poly-cone 12" woofer, fantastic (but impossible) frequency
    response, 98 db/watt sensitivity, and so on.

    These speaker are made by a couple of manufacturers with the
    intent of being sold exactly this way.  They cost the kids in
    the van about $100 a pair, and the kids are given minimal
    training about what kinds of stories to use, what parking lots
    are the most likely to generate sales (department store parking
    lots near colleges in September is a great time for these guys).
    Anything over and above the $100 dollars the kids paid is pure
    profit (except for gas money).

    Stay away, you're getting ripped off.

9.7 What speakers should I consider in the $XXX/pair price range?
    This is probably the most commonly asked question on rec.audio,
    and also the most impossible to answer.  The market keeps
    changing, everyone has different tastes, and no one has the time
    to listen to even 10% of the products available in any country.
    Also, many good products are only available in specific regions
    or countries.

    If you really want recommendations and are willing to listen to
    the opinions of others, check the past few issues of Stereophile
    Mag.  Although they are strongly biased towards very expensive
    gear and have their own particular other biases, they do steer

    you to some very good equipment in their frequently-updated list
    of "RECOMMENDED COMPONENTS".

9.8 Can you build better speakers than you can buy?
    Some people can build better than you can buy.  These people are
    either experts, golden ears, extremely well equipped, inspired,
    or a combination of the above.

    Some companies have plans available to entice you into buying
    their drivers: Audio Concepts, Audax, Dynaudio, Focal, KEF, and
    Scanspeak.  Your success rate with these plans will probably be
    very good IF your cabinetry skills are very good and IF you
    follow the plans precisely.  If you deviate (as everyone does),
    anything is possible.

    Stereophile has published three different plans designed by Dick
    Olsher which are similar two-way ported systems. A recent one of
    these was in Stereophile Nov '90, pages 94-127. Audio Magazine
    published a plan called "The Pitts" by Ken Kantor, in Audio, Nov
    '88 pages 65-71 continued in Dec '88 pages 73-77.  This plan is
    a two-way sealed box.

    I have built one published design and one manufacturer's design.
    I believe that both met my expectations.  They took me a long
    time to build, taught me a lot, were fun projects, and sounded
    good when finished.

    I also believe that a commercial system which cost what my parts
    cost will never sound anywhere near as good as the one I build.
    If you consider $2/hour for my time, however, building is
    financial suicide.

    Designing your own system is even more a can-of-worms, and
    should be left to those with either a strong stomach, a very
    forgiving ear, infinite resources, or excellent guidance.

9.9 Where can I read more about speaker building?
    Speaker Builder Magazine
        Audio Amateur Publications
        PO Box 494
        Peterborough NH  03458 USA
        603-924-9464
    The Loudspeaker Design Cookbook, Fourth Edition
        by Vance Dickason (C) 1991
        ISBN 0-9624191-7-6
        $29.95 + $2.00 S&H from
        Old Colony Sound Lab
        PO Box 243
        Peterborough NH  03458-0243 USA
        603-924-9464
    High Performance Loudspeakers by Martin Colloms
    Synergetic Audio Concepts Classes and Newsletters
        Syn-Aud-Con teaches classes on Audio and Acoustics
        12370 W. Co. Rd. 100 N.
        Norman IN  47264 USA
        812-995-8212
9.10 Where can I buy speaker drivers?
    A & S Speakers (Broad line)
        3170 23rd Street
        San Francisco CA  94110 USA
        415-641-4573
    Audio Concepts (Their own kits plus drivers)
        901 South 4th Street
        LaCrosse WI  54602 USA
        800-346-9183
    Phil Baker (Surplus cabinets only)
        546 Boston Avenue
        Medford MA  02155
    Carbonneau
        609 Myrtle NW
        Grand Rapids MI  49504 USA
        616-456-9528
    Drexler Audio Systems (Bandor Speaker Distributor)
        14 Rose Lane
        Rosemont PA  19010
    Gold Sound (Broad line including pro speakers)
        PO Box 141
        Englewood CO  80151 USA
        303-789-5310
    Madisound (Broad line)
        8608 University Green
        Box 4283
        Madison WI  53711 USA
        608-831-3433
    McGee Electronics (Polydax, Pyle, Motorola, EV, MTX)
        1901 McGee Street
        Kansas City MO  64108-1891 USA
        913-491-5287 or 800-876-2433
    Meniscus
        2442 28th Street SW Ste D
        Wyoming MI  49509 USA
        616-534-9121
    Parts Express
        340 East First Street
        Dayton OH  45402-1257 USA
        513-222-0173
    Solen Electronique (Airborne, Audax, Ceratech, Dynaudio, Eton,
        Lpg, Morel, Peerless, Scan-Speak, Seas, Solen, Vifa)
        4470 Avenue Thibault
        St.-Hubert, QC  J3Y 7T9 Canada
        Voice 514-656-2759
        FAX [phone]
    Speakers Etc.
        1828 West Peoria Avenue
        Phoneix AZ  85029 USA
        602-944-1878
    SRS Enterprises (Pyle, Pioneer)
        318 South Wahsatch Avenue
        Colorado Springs CO  80903 USA
        719-475-2545
    Transducer Technology (Cabasse, Accuton, Vieta,
            Audiom by Focal, Stage, Tekton)
        4320 Spring Valley Road
        Dallas TX  75244
        214-991-6994
    Zalytron (Broad line including kits)
        469 Jericho Turnpike
        Mineola NY  11501 USA
        516-747-3515

9.11 Where can I buy loudspeaker kits?
    Audio Concepts, Inc. (Wide range of kits.  Catalog available)
        901 South Fourth Street
        La Crosse WI  54601 USA
        608-784-4570
    Fried Products (Parts kits starting $550.  Catalog available)
        (Emphasizes high-end transmission line speakers)
        (Parts kits have plan, crossover, and driver)
        Conshocken Road
        Conshocken PA  19428 USA
        215-277-9004
    Mahogany Sound (Parts kits and Woodstyle kits)
        (Parts kits have plan, crossover, and driver)
        (Woodstyle kits also have 3/4" MDF veneered boxes)
        (Prices $150/pair to $500/pair.  Catalog available)
        (Two way, three way & subwoofer kits)
        2610 Schillingers Rd #488
        Mobile AL  36695 USA
        205-633-2054
    Also see above, under suppliers for speaker drivers.

9.12 How can I improve the sound of my speakers?
    The best way to change the sound of your speakers is to change
    where you put them.  Ideally, the speakers should be located at
    ear level, in front of you, squared off between you.  It's then
    a matter of fiddling with a) the angles, b) the distance apart,
    c) the distance from you, and d) the distance from the wall.
    Just moving the speakers around in the room or putting them onto
    stands can make a major difference. For more on speaker
    placement, see 13.1 below.

    Other than that, speaker modifications can be a can of worms, or
    can produce very subtle changes, which you might prefer.  For
    example, you might improve a speaker by adding some cross braces
    of 1"x1" wood from left to right and from front to back.  This
    will stiffen the cabinet and reduce speaker cabinet wall
    vibrations, which probably hurt sound quality.  Alas, this will
    be most effective with lower-cost and poorly built speakers.

    Along similar lines, some claim success putting lead wire or
    epoxy putty on thin parts of the speaker to damp out resonances.
    You can try doing this to the thinner parts of the speaker
    "basket" or frame, or to the front "baffle" or supporting panel.

    Still another "tweak" is to add sound deadening felt pads to the
    inside walls of the speaker.  Instead of felt pads some advocate
    sand-filled latex coatings on the inside walls of speakers.
    Others advocate ceramic tiles held in place with "thinset".
    Still others rave about commercial products like AC Glop,
    Acoustic Magic, and Bostik Sheet.  However, the people who rave
    about these products tend to be the same people who sell them.

    Any change along the lines of adding felt, cross-bracing, or
    putty will have subtle effects on the sound.

    For the brave at heart, you can replace old or cheap drivers
    with better ones, but the results of this one change can be very
    dissatisfying if you happen to get the wrong type of driver for
    that application, and may never sound right, even if you use a
    similar driver. Speaker system design is still somewhat of a
    science and somewhat of an art.  Throwing paint on a canvas
    often makes a mess.

    Whatever change you try, don't "burn your bridge" home.  Be sure
    that you can undo whatever change you did, just in case.  Many
    tweaks to good speakers, no matter how well thought through,
    will correct for one flaw, but create others, or correct a flaw
    that the designer had cleverly used to his advantage.

9.13 How can I replace/re-cone my old speakers?

    The best chance of success is to buy an identical replacement
    speaker driver from the manufacturer of the system.

    Second choice is to buy the exact same driver from a
    distributor.  This is sometimes difficult because it is hard to
    learn exactly what driver the manufacturer used.  In addition,
    EVEN IF the manufacturer used stock speakers, they might have
    used matched pairs or selected speakers by hand for an exact set
    of specific characteristics.

    There are companies that rebuild drivers, but they charge quite
    a bit.  I have heard $75 per driver. This is rarely done for
    anything but very expensive commercial drivers.  Speaker
    manufacturers will often sell owners the materials that they
    need to repair a speaker.  If you are handy with delicate
    things, it is worth a try.

    In addition to speaker manufacturers, there are companies which
    sells rebuild kits for approximately $30 per pair, containing
    new foam, a special glue, and instructions.  If you have a blown
    or distorted voice coil, this still won't help. A few netters
    have used rebuild kits from this company successfully. Contact:
        Stepp Audio Technologies
        PO Box 1088
        Flat Rock NC  38731 USA
        800-747-3692

|    Another vendor of speaker repair parts is:
        Simply Speakers
        P. O. Box 22673
        St. Petersburg FL  33742 USA
        800-767-4041 or 813-571-1245

    Some speaker manufacturers have very good warranties.
    Electro-Voice warranties all professional products for life.
    KEF has a similarly broad warranty on their speakers.  Contact
    the manufacturer first.

9.14 What computer programs can I use to design speakers?
    There are many useful programs available, but none are complete
    without a good knowledge of speaker design. Further, you will
    NEED to supplement any program with hand tweaking for the best
    sound.  Finally, no simulation program is ever useful without
    good model parameters, and the parameters which manufacturers
    give you are often imperfect, so many good designers strongly
    recommend your own lab measurements.  The Loudspeaker Design
    Cookbook (see 9.9) tells you how to measure a speaker, and also
    enough theory to feel confident with a good program.

    You can get a lot done with a simple spreadsheet and the
    equations in a book like The Loudspeaker Design Cookbook.

    Active Filter Designer by Fernando Garcia Ciesca
        $17.50.  Crossover design.
    BoxModel by Robert Bullock
        $50.00.  Sealed, vented, and passive radiator
        modeling below 400Hz.
    CACD by Scientific Design Software
        Crossover optimizer.
    CALSOD by Witold Waldman
        $65 basic model, $300 complete.
        Crossover optimizer.
    Crossover Design by G. R. Koonce
    Driver Eval by G. R. Koonce
        $25 for both.  Simple programs do what they say.
    Filter Designer 1 by SpeakEasy
        $195 Crossover design program
    Loudspeaker by Maximum Effort Software
        $65 Box design for many different enclosures
        plus crossover network design
    LEAP by Audio Teknology
        $295 to $895 depending on options.
        Complete multi-way design program.
    Low Frequency Designer by SpeakEasy
        $195 Design many different box types.
    LMP by Ralph Gonzales/Sitting Duck Software
        $49.50 Crossover characteristic display
    MacSpeakerz by True Image
        $249 Apple Macintosh box and crossover design
    ModelONE by TDR
        $288 Does auto sound design knowing the
        patterns of various car interiors
    Perfect Box (Shareware, $40 registration in US funds)
        Warren A. Merkel; 2851 Newcomb Ct; Orlando, FL 32826
        MS-DOS executable.  Simulation of low-frequency
        speaker performance (10Hz-200Hz).
        available by ftp from: wuarchive.wust1.edu
        directory /usenet/comp.binaries.ibm.pc/volume12/perf
    PXO by Robert Bullock
        $50 simple crossover design program
    Speak by DLC Designs
        $395 Does box design and crossover design
    Speaker Designer by Stuart Bonney
        $19.50 Low-frequency box design.
    Two-Way Active Crossover Design by Gary Galo
        $20 Simple crossover component calculation
    XOPT by Peter Schuck
        $199 Complete filter design; rumored to have bugs

9.15 Can I magnetically shield my speakers for use near a TV?
    You probably will need to buy speakers that are made with an
    integral magnetic shield.  Magnetic shielding is usually done
    by either shielding the speaker magnet or by cancellation of the
    magnetic field very close to the magnet, or by both.  Shielded
    speakers are NOT built by lining the enclosure with metal.
    While it sounds like a good idea, it doesn't work.

    A common magnet shield is a mild steel cup around the magnet.
    This is the cheapest shield, and is usually fairly ineffective.
    It also will interfere with the speaker's critical magnet gap,
    so this type of shield can hurt speaker performance by shorting
    the magnetic field and reducing the magnetic flux density in the
    gap, which can reduce efficiency and affect the speaker's low
    frequency performance.

    Cancellation is done using a reverse-polarized magnet glued to
    the back of the main magnet.  If done right, it can almost
    completely cancel the rear stray field.  In some cases it can
    also increase the magnetic flux density in the gap, which may
    or may not be desirable.

9.16 What are all of these abbreviations people use for speakers?
    Most of these parameters are well documented in the Loudspeaker
    Design Cookbook. (see 9.9)  In summary:

    Fs    Driver free air resonance, in Hz.  This is the point at
        which driver impedance is maximum.
    Fc    System resonance (usually for sealed box systems), in Hz
    Fb    Enclosure resonance (usually for reflex systems), in Hz
    F3    -3 dB cutoff frequency, in Hz

    Vas   "Equivalent volume of compliance", this is a volume of
        air whose compliance is the same as a driver's
        acoustical compliance Cms (q.v.), in cubic meters

    D     Effective diameter of driver, in meters
    Sd    Effective piston radiating area of driver in square meters
    Xmax  Maximum peak linear excursion of driver, in meters
    Vd    Maximum linear volume of displacement of the driver
        (product of Sd times Xmax), in cubic meters.

    Re    Driver DC resistance (voice coil, mainly), in ohms
    Rg    Amplifier source resistance (includes leads, crossover,
        etc.), in ohms

    Qms   The driver's Q at resonance (Fs), due to mechanical
        losses; dimensionless
    Qes   The driver's Q at resonance (Fs), due to electrical
        losses; dimensionless
    Qts   The driver's Q at resonance (Fs), due to all losses;
         dimensionless
    Qmc   The system's Q at resonance (Fc), due to mechanical
        losses; dimensionless
    Qec   The system's Q at resonance (Fc), due to electrical
        losses; dimensionless
    Qtc   The system's Q at resonance (Fc), due to all losses;
        dimensionless

    n0    The reference efficiency of the system (eta sub 0)
        dimensionless, usually expressed as %

    Cms   The driver's mechanical compliance (reciprocal of
        stiffness), in m/N
    Mms   The driver's effective mechanical mass (including air
        load), in kg
    Rms   The driver's mechanical losses, in kg/s

    Cas   Acoustical equivalent of Cms
    Mas   Acoustical equivalent of Mms
    Ras   Acoustical equivalent of Rms

    Cmes  The electrical capacitive equivalent of Mms, in farads
    Lces  The electrical inductive equivalent of Cms, in henries
    Res   The electrical resistave equivalent of Rms, in ohms

    B     Magnetic flux density in gap, in Tesla
    l     length of wire immersed in magnetic field, in meters
    Bl    Electro-magnetic force factor, can be expressed in
        Tesla-meters or, preferably, in meters/Newton

    Pa    Acoustical power
    Pe    Electrical power

    c     propogation velocity of sound at STP, approx. 342 m/s
    p     (rho) density of air at STP 1.18 kg/m^3

10.0 Amplifiers
    Note: A receiver contains an amplifier, so the following
|    questions apply to both receivers and amplifiers.  In the
|    following text, "amp" and "amplifier" are used synonymously.


10.1 What is Biamping? Biwiring?
    Most speakers are connected to an amplifier by one pair
    of terminals on each speaker. Within these speakers, a
    crossover distributes the signal (modified appropriately)
    to each of the drivers in the speaker.

    Some speakers are set up to be either biwired or biamped. A
    much smaller number allows triwiring and triamping.  The same
    principles apply but use three sets of wires or three amplifiers
    instead of two.  Most speakers that support biamping/biwiring
    have two pairs of terminals and some mechanism for shorting
    the two pairs together when used in the normal way. This
    mechanism is most likely a switch or a bus bar. To help
    the descriptions below, I will refer to these two pairs as
    LO and HI  (because normally one pair connects to the woofer
    and the other pair connects to the tweeter/midrange).

    Biwiring means that a speaker is driven by two pairs of wires
    from the same amplifier output. One cable pair connects HI to
    the amp, and the other cable pair connects LO to the same amp
    output that you connected the HI cable to.  Biwiring is
    controversial; some folks hear a difference, some do not. The
    most plausible explanation involves magnetic induction of noise
    in the relatively low current HI cable from the relatively high
    current signal in the LO cable.  Accordingly, Vandersteen
    recommends the two cable pairs for a channel be separated by at
    least a few inches. In any case, the effect appears to be small.

    Biamping means that the two pairs of terminals on a speaker are
    connected to distinct amplifier outputs. Assuming you have two
    stereo amplifiers, you have two choices: either an amp per
    channel, or an amp per driver. For the amp per channel, you
    connect each terminal pair to a different channel on the amp
    (for example, the left output connects to HI and the right side
    to LO). In the other configuration, one amp connects to the LO
    terminals, and the other amp is connected to the HI terminals.

    The point of biamping is that most of the power required to
    drive the speakers is used for low frequencies. Bimaping allows
    you to use amps specialized for each of these uses, such
    as a big solid-state amplifier for the LO drivers and higher
    quality (but lower power) amp for the higher frequencies.
    When you have two identical stereo amps, some folks
    recommend distributing the low-frequency load by using an amp
    per channel.  In any case, whenever you use two different
    amplifiers, be careful to match levels between them.

    Biamping also allows you to use high-quality electronic
    crossovers and drive the speaker's drivers (the voice coils)
    directly, without the series resistance and non-linear
    inductance of a passive crossover.  Biamping which uses the
    speaker's crossover is therefore much less desirable.  Replacing
    a good speaker's crossover with an electronic crossover has
    advantages, but involves some very critical tradeoffs and tuning
    which is best left to those well-equipped or experienced.

    See also section 16.0 below, on wire and connectors in general.

10.2 Can amplifier X drive 2 ohm or 4 ohm speakers?
    Almost any amplifier can drive almost any load if you don't turn
    the volume up too high.  Tube amplifiers are one exception.
    Some amps clip if you play them too loud.  This is bad and
    damages speakers.  Other amplifiers shutdown if they are asked
    to play too loud.  Many will overheat, with bad consequences.
    However, in almost all cases, it takes seriously loud sound or
    low speaker resistance (less than 4 ohms) to do damage.  Running
    two sets of 8 ohm speakers at once with common amplifiers
    represents a 4 ohm load.  Four sets of 8 ohm speakers makes a 2
    ohm load.  Two sets of 4 ohm speakers also makes a 2 ohm load.
    If you stay sober and don't turn it up past the point where it
    distorts, you are PROBABLY safe with most amplifiers and most
    loads.  See 10.3 for more information.

10.3 How do I drive more than two speakers with one stereo amplifier?
    One amp can drive many speakers.  However, there are two limits
    to this practice.  The first is that you can overheat or damage
    an amplifier if you drive too low of an impedance to loud
    listening levels.  Avoid loading any amplifier with a lower
    impedance than recommended.  Adding two speakers to one amp
    output loads that output with half the impedance of one speaker.
    (See also 10.2 above)

    The second is that with tube amplifiers, which are uncommon in
    today's common system, it is important that the speaker
    impedance and the amplifier output impedance be well matched.

    When driving two or more speakers from one amp output, always
    wire them in parallel, rather than series.  Series connection,
    while safe in terms of impedance levels, can hurt sound quality
    by raising the impedance that the speakers themselves see.

    Many amplifiers have connectors for two pairs of speakers.  In
    general, these amplifiers also have a speaker selector switch.
    These amplifiers almost exclusively connect the speakers in
    parallel when both are selected.  It is common for these
    amplifiers to specify 8 ohm speakers only.  The reason that they
    specify 8 ohm speakers is because the amplifier is built to
    drive either 4 or 8 ohms, and two sets of 8 ohm speakers loads
    the amplifier as if it were one set of 4 ohm speakers.  It is
    probably perfectly safe to connect one set of 4 ohm speakers to
    an amplifier with two sets of outputs, provided that you NEVER
    use the second set for any set of speakers.

10.4 How big an amplifier do I need?
    Unfortunately, amplifier power ratings and speaker power ratings
    are almost always misleading.  Sometimes, they are factually
    wrong.  Speaker ratings are almost useless in evaluating needs.

    More importantly, human hearing is sensitive to the log of the
    power coming out of the speaker.  This means that the perceived
    difference between an 80 watt amplifier and a 100 watt
    amplifier, all else equal, is very small. (under 1 dB!)

    There is a wide variation in the "efficiency" and "sensitivity"
    of the various speakers available.  I have seen good speakers
    with under 80 dB per watt efficiency and have also seen good
    speakers with over 96 dB per watt efficiency, measured one meter
    from the speaker.  This difference of 16 dB represents a factor
    of 40 difference in power requirement!

    So the first step in determining amplifier requirements is to
    estimate relative speaker efficiency.  Other factors include how
    loud you will want to listen, how large your room is, and how
    many speakers you will drive with one amplifier.  This
    information will give you a rough starting point.  For an
    example, a typical home speaker will produce 88 dB at 1 watt.
    In an average room, a person with average tastes will be happy
    with this speaker and a good 20 watt per channel amplifier.
    Someone who listens to loud music or wants very clean
    reproduction of the dynamics of music will want more power.
    Someone with less efficient speakers or a large room will also
    want more power.

    Past that point, you will have to use your ears.  As with all
    other decisions, your best bet is to get some candidates, borrow
    them from a friendly dealer, take them home, and listen to them
    at your normal and loudest listening level.  See if they play
    cleanly when cranked up as loud as you will ever go, into your
    speakers in your room.  Of course, it is also important to be
    sure that the amp sounds clean at lower listening levels.

10.5 Do all amplifiers with the same specifications sound alike?
    Some say that they do.  Some say that they don't.  Some
    demonstrated that many amplifier differences can be traced to
    very slight frequency response difference.  Let your own ears
    guide you.  If you want to compare amplifiers, you can do it
    best in a controlled environment, such as your home, with your
    music and your speakers.  Also be very careful to match levels
    precisely.  All you need to match levels of amplifiers is a high
    input-impedance digital voltmeter set to AC volts and a test
    recording or signal generator.

10.6 Is this amplifier too big for that set of speakers?
    There is no such thing as an amplifier that is too big.  Small
    amplifiers are more likely to damage speakers than large ones,
    because small amplifiers are more likely to clip than larger
    ones, at the same listening level.  I have never heard of
    speakers being damaged by an overly large amplifier.  I have
    heard of 100 watt speakers being damaged by a 20 watt
    amplifier, however, in really abusive hands.

10.7 Where can I get a cheap low-power amplifier?
    There are very few available.  One source is to buy a cheap boom
    box and only use the amplifier.  Another source is Radio Shack.
    A third alternative is to buy a car stereo booster and get a 12V
    power supply for it.  Finally, you can build an amp pretty
    easily if you are handy, but it probably won't be that cheap.
    Mark V Electronics, for example, sells 20 watt amp kits for
    under $30 and 80 watt amp kits for under $150.  (See 10.14,
    10.15, and 10.16.)

10.8 Is the stuff sold by Carver really awesome?
    Some people really like it.  Others believe that it doesn't
    perform up to specifications.  Still others believe that it
    isn't all that it is hyped up to be. One of Carver's claims to
    fame is lots of watts per pound of weight.  As with almost
    everything else, the best policy is to listen for yourself and
    see what you think.

10.9 What is a preamplifier?
    A preamplifier is an amplifying electronic circuit which can be
    connected to a low output level device such as a phono cartridge
    or a microphone, and produce a larger electrical voltage at a
    lower impedance, with the correct frequency response.  Phono
    cartridges need both amplification and frequency response
    equalization.  Microphones only need amplification.

    In most audio applications, the term 'preamplifier' is actually
    a misnomer and refers to a device more properly called a

    'control amplifier'.  Its purpose is to provide features such as
    input selection, level control, tape loops, and sometimes, a
    minimal amount of line-stage gain.  These units are not
    preamplifiers in the most technical sense of the word, yet
    everyone calls them that.
--
Bob Neidorff; Unitrode I. C. Corp.  |  Internet: [e-mail]
7 Continental Blvd.                 |  Voice   : (US) 603-424-2410
Merrimack, NH  03054-0399 USA       |  FAX     : (US) 603-424-3460
=========================================================================
·    Subject: rec.audio FAQ (part 2 of 4)

Archive-name: AudioFAQ/part2
Last-modified: 1993/3/8
Version: 1.2

10.10 What is a passive preamplifier?
    A passive preamplifier is a control unit without any
    amplification at all. It is a classic oxymoron, because it has
    no capability to increase the gain of the signal.  It is only
    used with line level sources that need no gain beyond unity.

10.11 Do I need a preamp?
    If you have a turntable, you MUST have a (real) preamp, or
    something with a phono preamp section.

    If you don't have a turntable, then the only value in a
    preamplifier is to select the signal source (tuner, CD player,
    etc) and adjust the volume.  If you only listen to CD's, skip
    the preamp entirely.  Get a CD player with a level control and
    connect it straight to a power amplifier.

    If you have a receiver, then the odds are that you already have
    all of the functions of a preamp.

10.12 Should I leave equipment on all of the time or turn it on and off?
    Some gear draws significant electricity, so you will waste money
    and fossile fuel if you leave it on all of the time.  As an
    example, a common amplifier consumes 40 watts at idle.  High-end
    gear uses far more electricity, but ignoring that, 40 watts x
    168 hours x 52 weeks x US $0.0001 per watt hour (rough estimate)
    is $35/year.  Now add a CD player, a preamp, and a tuner, and it
    really adds up.

    High-end enthusiasts claim that equipment needs to warm up to
    sound its best.  If you care about the best sound, give your
    equipment at least 20 minutes to warm up before serious
    listening.  Warm up will allow the inside temperature to
    stabilize, minimizing offsets, bring bias currents up to their
    proper values, and bringing gain up to operating level.

    Either way, good gear will last a very long time.  Tubes are
    known to have a finite life, but good tube designs run tubes
    very conservatively, giving them life exceeding 10 years of
    continuous service.  Some amplifiers run tubes harder to get
    more power out, and thereby may be more economical to turn off
    between use.

    Filter capacitors will fail after enough time at temperature
    with voltage applied.  They will last longer if turned off
    between use.  However, like tubes, filter caps can last tens of
    years of continuous use, as can power transformers,
    semiconductors, and the like.

    Filter capacitors have a funny problem that justified a simple
    break-in or reforming when they are restarted after many years
    of rest.  It involves bringing up the power line voltage slowly
    with a variable transformer.  For tips on reforming capacitors,
    consult "The Radio Amateur's Handbook", by the ARRL.

    Semiconductors seem to fail more often because of bad surges and
    abuse than age.  Leaving gear off may be best for semiconductors
    and other surge-sensitive gear if you expect power line surges,
    as come from an electrical storm or operation of large motors.

    Fuses seem to age with temperature and get noisy, but they are
    so inexpensive that it should not bias your decision.  However,
    some are inconvenient to change, and may require opening the
    case and even voiding the warranty.

10.13 What about swapping op-amps?
    Many amplifiers, receivers, preamplifiers, CD players, and
    mixers use integrated circuits (ICs) called operational
    amplifiers (op amps) as audio amplifiers.  The first op amps had
    a reputation for poor sound quality, especially if misused.
    Some engineers with a strong background in ICs and op amps
    learned that they could improve sound if they replaced slow,
    noisy, low slew-rate, or otherwise bad op amps with better ones.
    Some less informed people tried doing the same thing and made
    the sound worse.

    One pitfall with op amp swapping is that some op amps are more
    prone to unwanted oscillation than others.  The faster the op
    amp, the more likely it will cause an unwanted oscillation,
    which will really damage the sound.  For that reason, Joe may
    succeed in replacing 741 op amps with 5534 op amps in his gear,
    and you may fail in your gear.  It is dependent on the
    individual design, layout, etc.

    As technology and IC design expertise marches on, audio op amps
    are getting better and swapping is getting less and less useful.
    New op amps continue to appear that displace yesterday's best,
    but sound surprisingly similar to straight wire.

    All of that said, some of the better op amps for audio as of
    today include (* means very highly recommended):
        Single        Dual
        AD847        AD827
        AD797*
        NE5534        NE5532
        OP-27        AD712
        LT1115*        LM833
        AD811        NE5535
        AD841        AD842
        HA5112*        OPA2604*
        LT1057        OP249*
        LT1028

    With op amp part numbers, there is a lot of room for confusion.
    Here is a guide to the numbers that is often accurate but
    sometimes wrong:

    Op amp part numbers start with a manufacturer's prefix:
        Analog Devices uses AD
        Burr Brown uses OPA
        Linear Technology uses LT
        Motorola uses MC
        National uses LF and LM
        PMI uses OP
        Signetics uses NE and SE
        TI uses TL
    This can be confused because if TI copies a Signetics op amp,
    they may assume the Signetics prefix, or they may use their own.
    Fortunately, if the part numbers are the same, the circuitry is
    almost exactly the same as is the performance. (Note: almost)

    The next thing in the part number is two, three or four or five
    digits.  This is invariably the key to the part. There are some
    op amps with different numbers that are electrically the same,
    but if the numbers are the same, the parts are almost surely the
    same.  For example, an LM357N and an LM357J are electrically
    identical and will sound the same.

    Next is a letter or two indicating the op amp package and
    possibly how it has been tested and what tests it passed.
    Unfortunately, manufacturers haven't standardized these letters.
    Fortunately, you almost never care.  If it is a dual-inline
    (DIP) package and you are replacing a DIP, you shouldn't have to
    worry whether or not it is ceramic or molded.  Likewise, you
    rarely care if it has 100uV offset or 4mV offset for audio.
    Finally, you don't care if it wasn't tested at elevated
    temperatures because you will use it in your house, inside well
    ventilated gear.

    So in general, an NE5532J is a TL5532N, and an AD827JN will
    sound the same as an AD827LD.  If you aren't sure about some
    detail, call or write the IC maker and ask for a data sheet on
    the parts in question.  They will always send data sheets for
    free, and these data sheets contain details on the various part
    numbers, internal circuitry, and electrical characteristics.

10.14 Where can I buy electronic parts to make an amplifier?
    There are many commercial parts distributors that sell only to
    Corporations.  Their prices are often list, their supply is
    often good, and their service varies.  Common ones are Arrow
    Electronics, Gerber Electronics, Hamilton Avnet, and Schweber
    Electronics.  See your local phone book.

    There are also distributors that cater to smaller buyers  These
    typically have only one office.  Some have lousy selections but
    great prices.  In the following list, (+) means that the dealer
    has a good reputation, (?) means that the dealer has
    insufficient reputation, and (X) means that some have reported
    problems with this dealer. (C) means they have a catalog.

    All Electronics Corporation (Surplus, Tools, Parts) (?) (C)
        PO Box 567
        Van Nuys CA  90408 USA
        800-826-5432
        818-904-0524
    Allied Electronics (Full Line of Parts) (+) (C)
        800-433-5700
    Antique Electronics Supply (Tubes, capacitors, etc) (?)
        688 First St
        Tempe AZ  85281 USA
        602-894-9503
    DigiKey Corporation (Full Line of Parts) (+) (C)
        701 Brooks Avenue South
        PO Box 677
        Thief River Falls MN  56701-0677 USA
        800-344-4539
    Maplin (European Parts) (?) (C)
        [phone] (For Orders Only)
        [phone] (Customer Service)
    Marchand Electronics (?) (Crossover kits)
        1334 Robin Hood Lane
        Webster NY  14580 USA
        716-872-5578
    MCM Electronics (Speakers, A/V Repair Parts, Etc) (+) (C)
        650 Congress Park Dr
        Centerville Ohio 45459-4072 USA
        513-434-0031

    MesaBoogie (Tubes, instrument speakers) (?)
        707-778-8823
    Mouser Electronics (Full Line of Parts) (+) (C)
        PO Box 699
        Mansfield TX  76063-0699 USA
        800-346-6873
        817-483-4422
    Newark Electronics (Full Line of Parts) (+) (C)
    Parts Express (Speakers, Cables, Connectors) (+) (C)
        340 East First Street
        Dayton OH  45402-1257 USA
        513-222-0173
    Radio Shack (Parts, Low-End Audio) (+) (C)
    Old Colony Sound (Audio parts and audio kits) (+) (C)
        PO Box 243
        Peterborough NH  03458-0243 USA
        603-924-9464
    Michael Percy (Connectors, MIT, Wonder Caps, Buf-03) (+)
        PO Box 526
        Inverness CA 94936 USA
        415-669-7181 Voice
        415-669-7558 FAX
    Tanner Electronics (Surplus Parts) (+)
        214-242-8702
    Triode Electronics (Tubes, transformers, boxes) (?)
        2010 Roscoe Street
        Chicago IL  60618
        312-871-7459
    Welborne Labs (Connectors, Linear Tech ICs, Wima Caps) (?)
        6836 South Universtiy Blvd. #70
        Littleton CO  80122 USA
        303-470-6585 Voice
        303-791-7856 FAX

10.15 Where can I buy audio amplifier kits?
    Alas, Heath is no longer making Heathkits. Alternatives:
    Audio Synthesis (Many kits from Ben Duncan designs) (?)
        99 Lapwind Lane
        Manchester M20 0UT, UK
        061-434-0126 Voice
        060-225-8431 FAX
    Old Colony Sound (+) (See 10.14)
    Hart Electronics (UK) (?)
    Hafler (+)
    Crimson (UK) (?)
    Mark V Electronics (?)
        8019 E Slauson Ave
        Montebello CA  90640 USA
        800-423-3483
        213-888-8988
    Sonic Frontiers Inc (Tube amp and preamp kits) (?)
        760 Pacific Road Unit #19
        Oakville, Ontario Canada L6L 6M5

10.16 Where can I read more about building amplifiers, preamps, etc.?
    Analog Devices Audio/Video Reference Manual
    Audio Amateur Magazine
        Audio Amateur Publications
        PO Box 494
        Peterborough NH  03458 USA
        603-924-9464
    Audio IC Op-Amp Applications, by Walter Jung
        OpAmp Technical Books
        213-464-4322
    Electronic Music Circuits, by Barry Klein
        Howard D Sams & Co ISBN 0-672-21833-X
|    Electronics Australia (Magazine with audio projects)
|        AUD47 per year 12 issues, often discounted
|        PO Box 199
|        Alexandria, Austrailia
|        [phone] or [phone]
    Elektor Electronics (How it works and you-build articles)
        (no longer published in US. Still available in Europe)
        PO Box 1414
        Dorchester DT2 8YH, UK
    Enhanced Sound: 22 Electronic Projects for the Audiophile
        (Some basic projects and some "how it works")
        by Richard Kaufman
        Tab Books #3071/McGraw Hill
        ISBN 0-8306-9317-3
    Glass Audio Magazine
        Audio Amateur Publications
        PO Box 494
        Peterborough NH  03458 USA
        603-924-9464
    IC Op-Amp Cookbook by Walter Jung
        OpAmp Technical Books
        213-464-4322
    Journal of the Audio Engineering Society (Theory & Experiment)
        Audio Engineering Society
        60 East 42nd Street
        New York City NY  10165-0075 USA
        212-661-2355
    Popular Electronics
    Radio-Electronics
    Radiotron Designer's Handbook, Fourth Edition (old, tube info)
    The Technique of Electronic Music, by Thomas H Wells
        Schirmer Books ISBN 0-02-872830-0
    Vacuum Tube Amplifiers, MIT Radiation Lab series
    Wireless World

10.17 What is Amplifier Class A?  What is Class B?  What is Class AB?
    What is Class C?  What is Class D?

    All of these terms refer to the operating characteristics
    of the output stages of amplifiers.

    Briefly, Class A amps sound the best, cost the most, and are the
    least practical. They waste power and return very clean signals.
    Class AB amps dominate the market and can rival the best Class A
    amps in sound quality.  They use far less power than Class A,
    and can be cheaper, smaller, cooler, and lighter.  Class D amps
    are only used for special applications like bass-guitar amps and
    subwoofer amps.  They are even smaller than Class AB amps and
    more efficient, yet are often limited in bandwidth to under
    20kHz (less than full-range audio). Class B and Class C amps are
    not useful for audio.

    In the following discussion, we will assume transistor output
    stages, with one transistor per function.  In some amplifiers,
    the output devices are tubes.  Most amplifiers use more than one
    transistor or tube per function in the output stage to increase
    the power level.

    Class A refers to an output stage with bias current greater than
    the maximum output current, so that all output transistors are
    always conducting current.  The biggest advantage of Class A
    operation is that it is most linear, in other words, it has the
    lowest distortion.

    The biggest disadvantage of Class A is that it is least
    efficient, in other words, it takes a very large Class A
    amplifier to deliver 50 watts, and that amplifier uses
    lots of electricity and gets very hot.

    Some high-end amplifiers today are Class A, but traditional
    Class A only accounts for perhaps 10% of the small high-end
    market and none of the middle or lower-end market.

    Class B amps have output stages which have zero idle bias
    current.  Typically, a Class B audio amplifier has zero bias
    current in a very small part of the power cycle, to avoid
    nonlinearities.  Class B amplifiers have a significant advantage
    over Class A in efficiency because they use almost no
    electricity with small signals.

    Class B amplifiers also have a major disadvantage: very audible
    distortion with small signals.  This distortion can be so bad
    that it is objectionable even with large signals.  This
    distortion is called crossover distortion, because it occurs at
    the point when the output stage crosses between sourcing and
    sinking current.  There are almost no Class B amplifiers on the
    market today, at any price.

    Class C amplifiers are similar to Class B in that the output
    stage has zero idle bias current.  However, Class C amplifiers
    have a region of zero idle current which is more than 50% of
    the total supply voltage.  The disadvantages of Class B
    amplifiers are even more evident in Class C amplifiers, so
    Class C is likewise not practical for audio amps.

    Class A amplifiers often consist of a driven transistor
    connected from output to positive power supply and a constant
    current transistor connected from output to negative power
    supply.  The signal to the driven transistor modulates the
    output voltage and the output current.  With no input signal,
    the constant bias current flows directly from the positive
    supply to the negative supply, resulting in no output current,
    yet lots of power consumed.

    Class B amplifiers consist of a driven transistor connected
    from output to positive power supply and another driven
    transistor connected from output to negative power supply.
    The signal drives one transistor on while the other is off,
    so in a Class B amp, no power is wasted going from the
    positive supply straight to the negative supply.

    Class AB amplifiers are almost the same as Class B amplifiers
    in that they have two driven transistors.  However, Class
    AB amplifiers differ from Class B amplifiers in that they
    have a small idle current flowing from positive supply to
    negative supply even when there is no input signal.  This idle
    current slightly increases power consumption, but does not
    increase it anywhere near as much as Class A.  This idle current
    also corrects almost all of the nonlinearity associated with
    crossover distortion.  These amplifiers are called Class AB
    rather than Class A because with large signals, they behave like
    Class B amplifiers, but with small signals, they behave like
    Class A amplifiers.  Most amplifiers on the market are Class AB.


    Some good amplifiers today use variations on the above themes.
    For example, some "Class A" amplifiers have both transistors
    driven, yet also have both transistors always on.  A specific
    example of this kind of amplifier is the "Stasis" (TM) amplifier
    topology promoted by Threshold, and used in a few different
    high-end amplifiers.  Stasis (TM) amplifiers are indeed
    Class A, but are not the same as a classic Class A amplifier.

    Class D amplifiers use pulse modulation techniques to achieve
    even higher efficiency than Class B amplifiers.  As Class B
    amplifiers used linear regulating transistors to modulate output
    current and voltage, they could never be more efficient than
    50%.  Class D amplifiers use transistors that are either on or
    off, and almost never in-between, so they waste the least amount
    of power.

    Obviously, then, Class D amplifiers are more efficient than
    Class A, Class AB, or Class B.  Some Class D amplifiers have
    >80% efficiency at full power.  Class D amplifiers can also have
    low distortion, although not as good as Class AB or Class A.

    Class D amplifiers are great for efficiency.  However they are
    awful for other reasons.  It is essential that any Class D amp
    be followed by a passive low-pass filter to remove switching
    noise.  This filter adds phase shift and distortion.  It also
    limits the high frequency performance of the amplifier, such
    that Class D amplifiers rarely have good treble.  The best
    application today for Class D amplifiers is subwoofers.

    To make a very good full range Class D amplifier, the switching
    frequency must be well above 40kHz.  Also, the amplifier must be
    followed by a very good low-pass filter that will remove all of
    the switching noise without causing power loss, phase-shift, or
    distortion.  Unfortunately, high switching frequency also means
    significant switching power dissipation.  It also means that the
    chances of radiated noise (which might get into a tuner or phono
    cartridge) is much higher.

11.0 CD Players, CDs, Turntables, and LPs

11.1 What should I listen for when evaluating a turntable or CD player?
    For tape decks and turntables, the major specific problems are
    caused by speed variations (wow and flutter).  A good specific
    check for this is Richard Strauss' 'Also Sprach Zarathustra'
    (also known as the theme from 2001), which has a long, low,
    sustained organ note which comes in well before the main theme
    starts, and is held through the entire first movement.
    Concentrate on that, and make sure it doesn't wobble or warble.
    There's also a good bit for that at the beginning of Pink
    Floyd's 'The Wall', but it doesn't go on as long and so means
    you've got less time to think about it.  Tape decks are
    also prone to losing high-frequency notes, so pick something
    you like which has a lot of treble, and make sure it is clear.

    The sound of a turntable is largely bound up in the kind of
    cartridge mounted on it.  Make sure to listen to a table with
    a cartridge similar to what you're buying, and not one in a
    different price bracket.  If possible, audition the turntable
    with the exact same arm and cartridge, so that you will
    experience potential cartridge/arm interactions, too.  Some
    excellent cartridges work better with one excellent arm than
    another excellent arm.  Treat the tonearm/cartridge pair as a
    coupled system, rather than independent components.

    For CD players, try some piano music.  See if the high notes
    sound tinny.  Also, try something which has some soft parts --
    not the same as turning the volume down.  The distortion
    specification for CD players (as for other devices) is measured
    at a high output level, but in fact in CD players (unlike
    others) it's actually likely to be worse in soft passages of
    music.  This is purely a function of the arithmetic involved.
    Most classical orchestral recordings will contain a suitable
    soft passage.  Most rock music won't.

    The distortion in a CD player, if you want to call it that, is
    a function of the granulation noise, or time-delay pre-echo that
    can come out of the filtering.  To listen for this, use material
    that is rich in high-order harmonics.  Brass music is great for
    this.  Unfortunately, you can't reliably predict how a CD player
    will sound by looking at specifications, features, or the
    technology it uses.  If you want to know how a player will
    sound, you have to listen to it.

11.2 Are some discs better than others?
    Some recordings are better than others.  Some artists are better
    than others.  Some recording engineers are better than others.
    Some microphones are better than others.  Some music is better
    than others.

    Ignoring the above, there is some difference between discs.
    Some of the very earliest discs were badly made and deteriorated
    with time.  The technical problems that caused those problems
    have been solved.  They included ink from the top bleeding into
    the disc, separation of the disc into two thin halfs, and
    oxidation of the metal inside.  Also, some discs were made which
    have aluminum going all the way to the edge of the disk, so are
    more prone to oxidation

    Some "gold" discs are available which are advertised to have
    better life and quality than common "aluminum" discs.  These
    sell for an extra US $20 or more per disc over the cost of the
    same music on a common disc.  Studies have shown that there is
    an advantage to glass-encased, gold platters for archiving
    computer data that is not error tolerant and will need to be
    stored for many tens of years.  I have yet to see a similar
    comparison which justified any extra effort for storing audio
    recordings for 50 years.  Part of the reason for this is that
    audio recordings contain error correction codes.  Another reason
    is that audio recorders can effectively reconstruct badly
    damaged audio data, even if there is data completely missing.

    Some discs seem to have pinholes in the aluminum, which are
    visible when the disc is held up to a strong light.  However,
    these discs play fine and last very well, so the effect of these
    pinholes is probably nil.  Some have performed studies counting
    errors on various discs with various players.  They found that,
    in general, the error count was consistent from one player to
    another.  Also, in general, most discs have a low, consistent
    error rate which is perfectly correctable using the redundant
    data stored on the disc.  This study did find that one group of
    discs had a higher error rate than all of the rest.  This group
    was the promotional discs, also called "music samplers" given
    away by music companies to introduce you to their family of
    artists and performers.  Despite these higher error counts,
    these discs still played fine.

    If there is no abusive handling involved, I have rarely heard of
    a disc that degraded with time.  Of the few that have existed,
    they tended to be from one of the bad batches mentioned earlier.

    There is no doubt that some discs are mastered better than
    others.  Some are badly mixed.  Some are so badly recorded that
    there is noticeable clipping.  Some are made from damaged master
    recordings.  CD technology is no guarantee of good music or of a
    good recording.

11.3 Are CDs better than LPs?
    Some excellent recordings are mastered digitally, and sound
    great on LPs.  This suggests that there is nothing inherently
    bad about digital.

    Some find that LPs sound better than CDs.  Advocates of LPs
    claim that the digital to analog (D/A) converter in home CD
    players isn't up to the quality of the information on the disc.
    They also claim that the analog electronics in a home CD player
    can be poor.

    Some believe that CDs do not sound like LPs because the CD does
    not have the frequency response errors, the distortion, or the
    stereo separation problems of LPs.

    In general, though, there are good and bad CD players, just as
    there are good and bad turntables, cartridges, and tone arms.
    Any ultimate comparison would require ultimate equipment, which
    is unaffordable.  In moderately priced systems, there will be
    some signal damage from the turntable system and some signal
    damage from the CD player.

    LP lovers often learn the nuances of cartridge selection, record
    care, and even turntable and tonearm adjustment.  They have
    found that the turntable will sound different if the arm height
    is adjusted, if the cartridge angles are changed, and if the
    tonearm wire is moved.  CDs do not offer as many avenues for the
    home experimenter.

    However, Audio Amateur Magazine has published modification
    projects for CD players; particularly for Magnavox 560 and
    similar European players.  Audio Magazine has also published
    such articles.

11.4 What turntable should I buy?
    Despite improvements in motor technology, most great turntables
    use belt drive.  Rubber roller (idler) drive sounds the worst.

    Select a turntable with a very heavy platter for the least wow
    and flutter.  Give the platter a rap with your knuckle.  It
    should not "ring" like a cymbal. It should feel and sound dead.

    Also look for a turntable that has good isolation from base to
    stylus.  With the amp on and the turntable selected, but with
    the turntable motor off, put an old record on the turntable,
    lower the stylus onto the record, and then tap the edge of the
    base.  Not too hard, you don't want to send the arm flying.  At
    worst, you should hear (through the speakers) a quick 'thump'
    followed by silence; if you're lucky, you'll hear nothing at
    all.  If the sound continues beyond a quick 'thump', the
    mechanical isolation is not great, and you might want to look at
    some other make.  To perform this test with some turntables, it
    will be necessary to unplug the turntable power cord.


    If the turntable has a tonearm, try to evaluate the arm, too.
    A good arm should be adjustable in height. A good arm should
    allow cartridge adjustments. A good arm should accommodate a
    wide range of cartridges.  Despite this, some arms work better
    with high compliance cartridges, while others are at their best
    with low compliance.  Ask.

    The original AR Turntable was very well received when it was
    first made, and the current AR Turntable is still very respected
    for its price ($450 + arm).  Turntables made by Denon, Linn,
    Rega, Sota, and VPI are also recommended, but can cost more.

11.5 What phono cartridge should I buy for my older turntable?
    The $30 Grado ZTE+1 is a great value for any home user but a
    purist.  For the purist, there are still many choices, both
    moving coil and moving magnet.  Each sounds slightly different,
    and has its individual strengths.  The Sumiko Blue Point has
    been recommended at $125 along with the $125 Denon DL-160 and
    the $150 Shure V15 type V-MR.

11.6 Will phono cartridges still be around ten years from now?
    Most likely, there will still be cartridges available, but not
    in the variety available ten years ago.  They will become
    "Special Order" in some stores and unheard of in others.

    "Pro" or "DJ" cartridges will stay available in good supply,
    "Audiophile" cartridges will stay available and very expensive,
    "Mid-line" cartridges will become very scarce, and a few
    "Budget" cartridges will remain available in copious supply.
    At the same time, some makers will drop their cartridge lines
    completely.

11.7 Will LPs still be around ten years from now?
    There is a strong movement of collectors and purists who will
    keep their collections and buy good used discs.  Count on these
    people to keep the used disc market hot for 25 years longer.

    As for new music, almost none is being pressed today, and the
    art of cutting a master is being lost.  Some rejoice in its
    demise and others are in mourning.

    LP sales have increased recently in Japan and in the UK. Polydor
    is now re-releasing older recordings on vinyl, and will continue
    to press them as long as it is profitable.  Likewise, there are
    several re-releasing projects in Japan.  Some are for Jazz
    collectors and others are for pure analog as well as classical
    music lovers.  They are selling the LPs by subscription, with
    shipments every 2 or 3 months.  Each release includes about 20
    titles.  Japan has released over 100 LPs this way last year.

11.8 What about CD green pens?
    In a nutshell, save your money.

    A CD player "reads" information on the disc with a laser light
    beam.  Some believe that if you put a green stripe on the very
    perimeter of the disc, then the light beam will not reflect
    around inside the disc and will more clearly pick up the data.

    Scientific studies of the data coming off of the disc have
    failed to show any difference between a virgin disc and a green
    painted disc.  I have not heard of double blind listening
    comparisons that have proved that there are people who can hear
    the difference, although many have performed uncontrolled tests
    with positive results.

11.9 What about CD stabilizer rings?
    In a nutshell, save your money.

    The data coming off of the disc is a serial string of ones and
    zeros.  If this bit stream has jitter, then it may reach the D/A
    converter out of sync.  If this happens, then the actual analog
    signal recreated will have jitter, and won't be perfectly true.
    The vendors of stabilizer rings say that using these rings will
    reduce jitter and make a more perfect signal.  Vendors also
    claim that the rings can increase the mass of a disc, making it
    spin more smoothly, and reducing transient load on the power
    supply from the motor.

    Some players will not play discs that have stabilizer rings on
    them.  The clamp can't handle the thickness.  Other players play
    ringed discs, but do not play them well, because the disc motor
    was not built for the added load.

    With those exceptions, scientific studies of the data coming off
    of the disc have failed to show any improvement going from a
    virgin to a ringed disc.  I have not heard of double blind
    comparisons that prove that people hear the difference, either.

11.10 What about CD spray treatments (ArmorAll et al)?
    In a nutshell, save your money.

    Current wisdom is to avoid any disc coating or spray.  Some will
    definitely damage the disc.

    There are many theories on what ArmorAll can do to a disc.  One
    is that it reduces static which will attract the delicate head
    of the laser detector to the disc.  Another theory is that the
    cleaner will fill voids in the disc with silicone, thereby
    making it easier to read by reducing diffraction effects.

    Scientific studies of the data coming off of the disc have
    failed to show any difference between a virgin disc and a
    treated disc.  I have not heard of double blind listening
    comparisons that have proved that there are people who can hear
    the difference.

    One of the strongest proponents of ArmorAll issued a "recall" on
    his advice.  He now warns that ArmorAll can damage the disc.  He
    also advises that you can clean ArmorAll off treated discs with
    Dawn dish detergent.

11.11 Are 1-bit CD players better than multi-bit players?
    In a nutshell, they are virtually the same.

    There are some excellent sounding 1-bit players and some
    excellent sounding multi-bit players.  Some feel that the 1-bit
    technology has more future because it can be improved with the
    rapidly improving digital technology, while the multi-bit
    players improve with slowly improving analog technology.
    Multi-bit also has its advocates.

    All of the various D/A converters try to do the same thing, and
    try to achieve the exact same ideal performance.  How well they
    succeed is more a function of their skill and the quality of the
    parts that they buy than the technique that they use.  In other
    words, the architecture of a D/A converter is less important
    than the quality of its implementation.

11.12 Are three lasers better than one in CD players?
    Some players have one beam, some three.  All use one laser diode
    to generate the beam.  Three-beam is just a different method for
    doing track alignment.  Neither is better than the other.

    There are good 1-beam players and good 3-beam players.
    Manufacturers want advertising claims and "More Beams Is Better"
    sounded good to some marketing people.  Trust your ears.

11.13 Is the BMG 8-for-1 deal good?
    Yes.  You have to put up with their frequent mailings. You can
    elect the "POSITIVE OPTION" and not have to answer each mailing
    to avoid an order.  You should expect to pay approximately $2.00
    per disc for shipping and handling in the US and more elsewhere,
    but even at that price and assuming that you will buy one of
    their discs for $16.00, you still do well.  Assuming, of course,
    that you want at least eight of the discs that they are offering
    for sale.  Some states requires sales tax on BMG sales, and some
    states tax "free" discs, but the tax still is small compared to
    the discount from retail.

    BMG does not have a great selection and tends to sell very
    common titles.  Some rumored that BMG discs are inferior to the
    discs sold in normal retail chains.  This has not been
    substantiated.  In fact, BMG distributes their discs through
    retail chains, as well as through the mail, so you may get a BMG
    disc either way.

11.14 What should I do if there is a problem dealing with BMG?
    The number to reach BMG is 317-542-0414.  Their people have been
    very cooperative with me and others.  It is always good policy
    to confirm any phone call with a letter, restating the problem
    and the resolution you were promised over the phone.  It is good
    practice to write down the name of the person you speak with.

    If BMG sends you something that you didn't order, DON'T OPEN THE
    PACKAGE.  Write REFUSED on the package and put it back in the
    mailbox.  They will accept the return and credit your account
    for any charges.

11.15 How do I get out of the BMG racket?
    If you have taken any discs from BMG, you must either return
    what you have ordered or fulfill the terms of your original
    agreement.  This often means buying one disc at full price and
    paying for the shipping on all discs you ordered and received.

    Once you have done this, you can quit the club at any time.
    Take your next order form and mark it with a bold marker in
    large letters "CANCEL MEMBERSHIP" and mail it to: BMG COMPACT
    DISC CLUB, PO BOX 91413, INDIANAPOLIS, IN  46291 USA.  It may
    take a month to fully take effect, but they will honor your
    request.  While waiting for the cancel order to take effect, be
    sure to return all future order forms marked the same way.
    Otherwise, you may wind up with unwanted discs.

11.16 How do I get the most out of BMG?
    Only buy one disc at full price, fulfilling your obligation.
    Request the "POSITIVE OPTION" so that you save on postage.  Only
    buy from special fliers.  Every month, except November and
    December, they send out a "Two for half price then one free"
    flier.  They have almost all of the stuff in the regular fliers.
    They even offer "Buy one get two free" sometimes.  Wait for

    those special deals.  You can even order discs from an October
    catalog using the order form that came in the February catalog.

11.17 What is a 1-bit (Mash, Bitstream) D/A converter (CD player).

11.18 What is the best under-$200 CD player?
    Once, Magnavox (and the identical Philips) CD players were known
    for poor reliability.  They are much better today.  Some believe
    that for sound, an under-$200 Magnavox is as good as any in its
    price range.  Be sure to listen for yourself before you buy.

11.19 What is the best under-$500 CD player?
    Some recommend the Rotel 855 and 955.

11.20 What's wrong with the CD longbox?
    Some CDs are sold shrink wrapped in a square plastic storage box
    known as the jewel box.  This is the ideal packaging for CDs.
    The shrink lets you know that the disc is new and unopened.
    Other than that, the packaging is minimal.

    Unfortunately, most CDs are sold in a cardboard box that is more
    than 2X the size of the jewel box.  This "long box" is
    ecologically wasteful and useless.  It rarely contains
    additional information about the disc or the artists.  Its
    primary purpose is to discourage theft in retail stores, but it
    is even poor at that.  These boxes are BAD.

    A few stores use a reusable plastic long box.  When you buy a
    disc in one of these boxes, you take the disc and jewel box with
    you and leave the plastic long box with the cashier for reuse.
    Not perfect, but a good compromise.

11.21 How can I promote better CD packaging?
    Vote with your money.  Don't buy CDs packaged in the long box.
    If you go to a store and they have CDs in the long box, tell the
    owner that you never buy CDs in the long box.  Then find stores
    which don't use the disposable long box.

11.22 How can I clean a dirty CD?
    Use a drop of dish detergent and lots of clean water.  Do not
    rub.  Never rub or wipe in a circle.  Rinse the disc in running
    clear water, shake off most remaining drops, and lightly pat dry
    with a soft, clean cloth.

11.23 Can you repair a damaged CD?
    If the disc is lightly scratched on the bottom, then you can
    polish out the scratch and probably repair the disc perfectly.
    If there are lots of scratches or deep scratches, or there is
    damage on the top, you may be facing a lost cause.  The music
    information is immediately under the label.  If you scratched
    the reflective layer, the disc is normally unrecoverable.

    Before trying any repair, try washing the disc with clear water
    and a bit of liquid dish detergent.  Do not scrub or rub hard.
    Rinse the disc with clear water and shake off as much water as
    you can.  Finally, wipe the last few drops off with a soft,
    clean cloth, in a radial direction.

    SMALL scratches can be removed with a scrufty T-shirt and
    toothpaste, such as Tom's Toothpaste.

    You may wish to try a thin coating of Johnson's Klear floor wax
    on the bottom of the CD.  Often it will cover the scratches
    enough to allow playing.  The refractive index is pretty close
    to polycarbonate, so filled scratches will be nearly invisible.

    Noteworthy Music (800-648-7972) sells CD repair kits (#CDR 200,
    $11.99, one shipping unit).  They seem to work as advertised,
    although getting the disc to the point where you can't see any
    sign of the scratch does take real care and persistence.

    You can buy professional plastic polishing compounds at many
    hobby shops.  The ones used for polishing acrylics, plexiglas,
    etc. work.  Ordinary lapidary jeweler's polishes also work.
    You'll need a rough polish to remove the scratches, then tin
    oxide to polish to a mirror finish.  Telescope lens kits also
    work.  Finally, T-Cut, a car paintwork polish, works well for
    big scratches.

11.24 Can I add digital output to a non-digital-out CD player?
    Some Magnavox CD players using the Philips chip set can be
    modified.  Look for a SAA7220 IC.  If it has one, then it can be
    modified.  If you have experience modifying electronic
    equipment, follow this procedure:

    Take pin 14 of the SAA7220 IC and remove whatever terminating
    resistor is on it.  Connect it through a 560 ohm resistor to the
    input of a wide band pulse transformer.  Tie the other end of
    the primary of the transformer to ground.  Pulse Engineering
    PE65612, Schott Corp 6712540, and Scientific Conversions
    SC916-01 all will work.  Bypass the primary through a 620 ohm
    resistor.  Connect the output of the transformer to an RCA jack.
    Do not ground either side of the RCA jack. This output is now
    S/PDIF compatible. (Thanks for the tip to Positive Feedback)

11.25 What can I get in the way of a CD test disc?
    Many use the Hi-Fi News & Record Review test discs.  So far,
    these have received only positive comments.

    Chesky produces 2 test discs.  The first, "Chesky Jazz Sampler
    Volume I" contains some excellent imaging test signals (called
    LEDR), some well-recorded acoustic jazz, and other test signals.
    The second, "Chesky Jazz Sampler Volume II" has similar music &
    different tests.

    Stereophile produces two test discs.  The first seems of limited
    value.  The second just came out.

    Denon also produces two test discs.  The first, "Digital Audio
    Check" is more useful for home use.  The second, "Audio
    Technical" is more for repair shops and test-disc addicts.

11.26 How do the letters ADD on my CD relate to sound quality?
    The simple answer to this question is that there is no relation
    between the three letter code and sound quality.  Those three
    letters refer to the recording and mastering tools used in
    making the CD.

    The first letter refers to the recording process.  For example,
    a disc labeled ADD was ANALOG recorded, where a disc labeled
    DDD was DIGITALLY recorded.  Analog recording means that some
    form of conventional analog tape recorder was used, whether it
    be a two-track home-quality recorder or a very expensive
    wide-tape, high-speed, multi-track recorder.  Digital recording
    could be as simple as a two-track DAT recorder, or can be a
    much fancier multi-track digital recorder.

    The second letter refers to the "mastering" process.  Mastering
    refers to the processing which takes the initial analog or
    digital recording and mixes it down to two-track stereo,
    edits out flaws, equalizes for different sound, adjusts levels,
    and otherwise changes the signal.  All of this can be done with
    digital signal processors, and it can also be done with analog
    signal processors.  There are good machines available for this
    which are analog and good machines which are digital.

    The third letter refers to the final product, which for a CD is
    always a digital product.  I have seen discs that are labelled
|    as AAD, ADD, DAD, and DDD.
|
|    Future releases may not have this three letter code on them
|    because they don't tell you anything that is significant. Also,
|    some codes have been used incorrectly on some discs, which
|    makes the information that much more meaningless.

12.0 High Fidelity Systems
    People frequently use the term "Stereo" to refer to a sound
    reproduction system.  To be more accurate, we will use the term
    High Fidelity System to refer to a pile of equipment including
    at least one source, at least one amplifier, and at least one
    speaker.  Common sources are turntables, CD players, tape
    players, tuners, and receivers.

12.1 What is a receiver?
    A receiver is a tuner, power amplifier, and preamp combined.  A
    common receiver has inputs for a turntable, a CD player, a tape
    deck, and perhaps one or two other sources.  It has selector
    switch(s), tone controls, and a volume control.  A receiver may
    have outputs for two speakers, or for more.

12.2 What is a tuner?
    A tuner is a radio receiver which can not directly connect to
    speakers.  Sometimes, the radio in a tuner is higher quality
    than the radio in a receiver.  A tuner may or may not receive
    the AM broadcast band, but 99.999% will receive the FM broadcast
    band.  Some also receive short wave bands, frequencies used
    principally by non-US stations.

12.3 How should I go about selecting a system?
    If you're looking to buy something, the first step is to figure
    out what you can spend.  If you're looking for a whole system,
    this gets tricky, because you have to allocate amounts for the
    different components.  The most popular current rule-of-thumb
    for a single source system (speakers, amp, 1 something-player)
    is to divide the money about equally among the three parts.  If
    you want several players, you'll have to decide whether they are
    all equally important, and so deserve the same amount of money;
    or whether some are less important, in which case you can spend
    less on them and put the savings elsewhere.

    This rule isn't hard-and-fast.  It's just meant as a starting
    point so you don't have to listen to every possible combination
    of equipment.  If you are building around a CD player, you might
    spend a bit less on the player and a bit more on the speakers.
    If you are buying turntable (or something else which plays by
    physical contact) on the other hand, it might be good idea to
    put a bit extra into the player.  The reason for this is that if
    you skimp on the turntable, then when you come to buy a better
    one you may find that your records have been worn out by the
    cheap player.  If you skimp on the speakers, on the other hand,

    then when you can afford better speakers the music will still be
    there on your records.

    See also 9.1, 9.2, and 11.1 for information on what to listen
    to and what to listen for when evaluating speakers, turntables,
    CD players, tape recorders, and systems in general.
--
Bob Neidorff; Unitrode I. C. Corp.  |  Internet: [e-mail]
7 Continental Blvd.                 |  Voice   : (US) 603-424-2410
Merrimack, NH  03054-0399 USA       |  FAX     : (US) 603-424-3460
=========================================================================
·    Subject: rec.audio FAQ (part 3 of 4)

Archive-name: AudioFAQ/part3
Last-modified: 1993/3/8
Version: 1.2

12.4 How can I improve the sound of my stereo?
    The cheapest improvement you can make, and perhaps the most
    effective, is to position your speakers carefully and correctly.
    See 9.4, above.  This will improve the frequency response
    flatness, making it easier to hear every instrument and voice.
    Setting speaker position correctly can also improve the
    three-dimensional recreation of a stereo image.

12.5 Do I want a combo system or separate components?
    Combo systems used to be cheap jokes; that's not always true
    now.  Some sound very nice; there are even some made by
    "audiophile" companies, and they sound even nicer.  They've got
    lots of advantages.  They take up less space.  The controls tend
    to be well-integrated, especially if they are remote-controlled.
    Therefore, they are easy to operate; this can be a major plus if
    some of the people who'll use it are afraid of, or not very good
    at, technology.  Also easy to set up, and don't leave millions
    of wires dangling all over everywhere.

    If you do go for a combo, get a brand name; either an audiophile
    company, or a good "consumer electronics" company.  Brand-X
    combos are generally overpriced and unpleasant.  If possible,
    buy it where you can listen to it first, such as a "real" hi-fi
    shop.  Mid-range hi-fi shops sell combos, as a way of
    introducing beginners to quality sound.

    In most good combos, the speakers are the weak link.  If you do
    go for a combo, you can almost always improve the sound
    drastically by buying a set of better speakers.  Better speakers
    start in the $100-$200 price range.  Some of the best combos
    come without speakers, forcing you to do this.  A good combo
    with replacement speakers will give you very pleasant music.

    Sounds good, you say, so why do people bother with components?
    Well, you can get better sound with a component system -- but
    usually at the expense of convenience and size.  A good
    component system will normally require a mixture of boxes from
    different makers to get the best results, so you've got to spend
    more time listening to things.  However, if you listen to your
    music seriously, then the performance of a component system is
    the reward for that extra work.

    Components are harder to set up and operate.  However, as noted,
    you can get better sound.  You also get more flexibility.  If,
    for example, you decide you want a better CD player, you just
    replace the CD player.  With a combo system, you've got to
    replace the whole system.  If your component tape deck breaks,
    you can remove it from the system and take it in for repair or
    replacement. With a combo, the whole system has to go in for
    repair or be replaced.

    When you want to add some new recording medium to your system
    (laserdisc, VCR, DAT, DCC, MD, ...), if you've got components
    you just go buy the appropriate box.  Many combo systems do not
    have places (or many places) to attach extra bits, so again you
    could be looking at replacing the whole thing.  With a component
    system, you can add a turntable; most modern combos can't cope
    with turntables any more.  Do you have a record collection?

    If you're really not sure, components are the safer bet; if
    you're going to make a mistake, that's probably the better way
    to be wrong.  But, if you're sure that a combo would be best
    for your needs, it can be a totally reasonable choice.

    Now, some people may be tempted by one-maker 'component sets',
    particularly the modern, miniature ones.  They tend to be
    equivalent to combos.  Most use non-standard connections, rather
    than the normal twin phono plug, so that it's likely you can't
    swap or add components anyway.  Even where they use standard
    interconnects, they may rely on non-standard interconnections
    for control purposes.  In a few cases, they also rely on sharing
    power, with a power supply in only one of the boxes and the rest
    taking low-voltage connections from that.  And, no one maker
    makes the best everything.  By default, assume that they will
    have the same disadvantages (and most of the same advantages) as
    combos.  If it's important for it to work with "standard"
    components from other makers, be sure to ask before you buy.

    And, if you're in doubt, go for separate components.

12.6 How can I get better FM radio reception?
    A. Use a (better) antenna. (See 12.7 and 12.8 below)
    B. Use a (more) directional antenna. (See 12.7 and 12.8 below)
    C. Aim your directional antenna.  Rhombics are ungainly to move,
        but Yagis and dipoles are small enough to point right at
        the station.  With the dipole, to tune in a station to
        the East, run the antenna North-South.  With a Yagi,
        point the individual elements North-South with the
        smallest element on the East end.

12.7 How good are these compact FM antennas?
    For receiving, small is ugly.  The bigger the antenna (all else
    equal) the better.  Of course, all else is never equal, but
    these fancy, expensive mini antennas tend to be awful.  Some
    compensate for their small receiving structure with a small
    antenna signal amplifier.  However, the quality of that
    amplifier is often no better than the quality of the amplifier
    in your tuner or receiver, so the antenna just gives you a
    stronger signal, complete with stronger noise.

    All of that said, some compact FM antennas can work better than
    a simple dipole in some situations.  They tend to have an
    internal amplifier, which helps with weak signals.  Some are
    directional.  Some aren't.  If possible, be sure that whatever
    you buy can be returned for a refund if it doesn't work out well
    for you.

12.8 What makes the best FM radio antenna?
    Although there is no "best" antenna for everyone, one of the
    most directional is the "rhombic".  Being very directional, this
    antenna can select one weak station out of many strong ones, or
    one group of stations originating from a general direction.
    This antenna is very long, and made up of four pieces of wire
    with feedline at one end for antenna connections and a resistor
    at the other for termination.  Rhombics for FM broadcast band
    use are at least 15 feet (4.5 meters) long, but can be made
    fairly narrow, less than 3 feet (1 meter) wide.  A more narrow
    antenna will be more directional. A longer antenna will give a
    stronger signal.

    Another very directional antenna is the "yagi", which looks just
    like a common TV antenna.  You can even use a common TV antenna
    as a very good FM antenna.  The FM and TV bands are very close
    together.  It has the advantages of being cheap, directional,
    and easy to rotate.

    One of the simplest and easiest to make antennas is the folded
    dipole, made from 300 ohm twin lead.  It is approx. 58" long.
    This antenna is surprisingly good for receiving signals in a
    moderately strong signal area.  Folded dipoles come with many
    tuners and receivers as a standard accessory.  They are also
    available for approximately $2 at audio and department stores.

    Whatever antenna you have, you can often get it to work better
    for specific stations by moving it.  In the case of the folded
    dipole, sometimes it works better vertically, and other times it
    works best horizontally.  Sometimes, you can get that one
    elusive station to come in perfectly if you bend the two ends of
    it at funny angles.  Don't be afraid to experiment.  One
    warning.  As atmospheric conditions change, the best antenna
    placement may also change.

    An excellent reference book on antennas is printed by the
|    American Radio Relay League (ARRL).  It is called The ARRL
|    Antenna Book.  Currently in its 16th edition, it is a 736
|    page large, illustrated paperback.  It costs $20 plus s/h.
    It has fairly complete antenna theory, practical information
    such as charts, drawings, comparisons, and tips on construction
    and adjustment.  The ARRL is founded and chartered as a
    non-profit organization to better amateur radio, and antennas
    are a vital part of amateur radio.
        American Radio Relay League
        225 Main Street
        Newington CT 06111 USA
|        203-666-1541

    Also useful:
        Practical Antenna Handbook by Joseph J. Carr
        Tab Books #3270/McGraw Hill - ISBN 0-8306-3270-3

12.9 What about power line conditioners?
    Each home and each outlet has slightly different power line
    impedance and power line noise.  Each amplifier is effected by
    power line impedance and power line noise differently.  Power
    line conditioners try to reduce this line noise.  Some also
    change the power line impedance in a way which is supposed to be
    better.  We will leave it to your ears to decide if these
    devices help the sound of your system enough to justify their
    expense.

12.10 How can I reduce vibration sensitivity?

12.11 What equipment can I buy that is 100% made in the USA?
    There are many lines of equipment that are carefully hand
    crafted in the USA.  Unfortunately, these systems are usually
    the high-end ones.  Some US companies also make gear in the
|    far east. When in doubt, ask. Some US audio manufacturers are:
|        Adcom (some made in Japan)
|        Audio by Van Alstine
|        Audio Research
|        California Audio Labs (CAL)
|        Carver
|        Jeff Rowland
|        Krell
|        Mark Levinson
|        McCormack

|        McIntosh
|        Parasound
|        Proceed
|        PS Audio
|        Spectral
|        Waida

13.0 Listening Rooms and Houses

13.1 How should I place speakers in my room?  What size room is best?
    You are after two important, distinct goals: flat frequency
    response and good three-dimensional image.  At your disposal is
    the room size, the room shape, speaker height, speaker
    placement, listening position, and room treatments.  Even though
    good speakers are essential to good sound, room effects are also
    extremely important.  In many cases, the differences in room
    effects will be more noticeable than spending twice as much on
    speakers!

    For smoothest bass response, a listening room should be as large
    as possible, have dimensions as unrelated as possible, and
    should be optimally damped.  Although nothing is ever ideal,
    there are a few room dimension ratios that are better for
    listening rooms:
        Height        Width        Length
        1        1.14        1.39
        1        1.28        1.54
        1        1.6        2.33
    If your room isn't shaped like that, don't worry.  These
    effects are not major.

    Also for smooth bass response, woofers should be at distances
    from the nearest three room boundaries that are as different as
    possible.  In some cases, the line dividing the listening room
    into left and right halves must be considered a room boundary.
    Also, for smooth bass response, the listener's ears should be
    at distances from the nearest three room boundaries that are
    as different as possible.

    All of this is essential because a wall near a speaker boosts
    the bass from that speaker at some frequencies.  If a speaker
    is the same distance from three walls, then some frequencies
    will be emphasized much more than others, rather than slightly
    more.

    For best three-dimensional image, a listening room should have
    good symmetry about the plane between the two speakers.  This
    means that if one speaker is in a corner, the other speaker
    must be in a corner.  If this symmetry is not right, the first
    reflection from the wall behind one speaker will be different
    from the first reflection from the wall behind the other speaker
    and critical parts of the stereo signal will be damaged.

    Also, no large object should block the path from speakers to
    listener or from speaker to speaker.  Speakers should be
    elevated so that tweeters are at listener ear height.  The
    distance between speakers should be no greater than the distance
    from each speaker to the listener.  Finally, the tweeters should
    be aimed at the listeners.

    A normal box-shaped listening room with bare walls will have
    "slap echo" which will reduce intelligibility.  A good cure is
    randomly-placed wall hangings consisting of small rugs spaced
    an inch or so away from the wall to increase sound absorption.
    Another cure is convex-shaped art objects on the walls to
    disperse harmful reflections.  If money is available, commercial
    room treatments such as "Tube Traps" and "RPG Diffusers" are
    also valuable, but many of the benefits of these exotic devices
    are available with simpler techniques.

    As a general rule, in a good room, speakers and listener can be
    close to room boundaries with minimal adverse effects.  In a bad
    room, a good strategy is to place both speakers and listener as
    far away from room boundaries as possible.

    An excellent starting point for speaker placement is to measure
    the listening room diagonal dimensions.  Divide that measurement
    by three.  Put each speaker that distance from a corner, on the
    room diagonals.

        I-----------------------------------I
        I                                   I
        I                 L                 I
        I                                   I
        I        S                 S        I
        I                                   I
        I-----------------------------------I

    Place your listening position midway between the two speakers
    and approximately half way from the speakers to the wall.  Be
    sure that there is nothing in the "triangle" formed by the
    listening position and the speakers.

    Try this and then move things 12" (30cm) at a time to see if
    you can improve the sound.  Your ears will be a better guide
    than any commonly-available instruments.  To keep track of
    what you are doing, take notes.  To remember exactly where
    you put the speaker on the floor, a practical trick is to
    mark the floor with a sewing needle and thread.

13.2 How do I wire a house for sound?
    A fundamental principle of physics is that the farther a signal
    travels, the more the signal will be degraded.  Translate this
    to mean that the shorter the wire, the better.  Understanding
    this, the idea of running speaker cable between  every room of
    the house isn't as attractive as it first seems.

    If you still decide to wire your house for sound, you should do
    it at the same time you're wiring for telephone and electricity.
    It is possible to wire a house after the walls are closed, but
    it becomes very difficult.

    It is economical to use common house wire (Romex, UF, NM, etc)
    for speaker wire in the walls, but this may violate building
    codes.  Check with an electrician or inspector first.  It will
    also confuse future electricians, so label the wire clearly, all
    along its length.

    If you want to make your house like a recording studio, it is
    best to use the techniques of recording studios.  When studios
    run long lengths of sound cable from one room to another, they
    drive the cable with 600 ohm line amplifiers.  They also use
    shielded, twisted-pair cable.  They only connect the shield at
    one end of the cable.  Finally, they use balanced inputs at the
    other end of the cable.

13.3 Where can I read more about listening room construction and tuning?
    "Building a Recording Studio" by Jeff Cooper
        Mix Bookshelf
    "Handbook for Sound Engineers"
    "The Master Handbook of Acoustics" by F Alton Everest
    "Sound Engineering 2nd Edition" by Don and Carolyn Davis;
        Howard W. Sams & Co. (C) 1990
    "Good Sound" by Laura Dearborn
        Introductory, but clear and accurate
    "Sound Recording Handbook" by John M. Woram
        Howard W. Sams & Co. #22583
        Excellent General Reference
    "Audio Technology Fundamentals" by Alan A. Cohen
        Howard W. Sams & Co. #22678
        Overview of Audio Theory
    "Introduction to Professional Recording Techniques"
        by Bruce Bartlett
        Howard W. Sams & Co. #22574
    "Modern Recording Techniques" by Hubar and Runstein
        Howard W. Sams & Co. #22682
    "Sound Studio Production Techniques"
        by Dennis N. Nardantonio
        Tab Books

14.0 Recording
    There are more different recording systems available today than
    ever before.  Digital and analog are both available to the
    consumer.  With the advent of consumer digital recorders, used
    pro analog recorders are becoming available for surprisingly low
    prices.  Now may be the time for you to buy a microphone and
    recorder and make your first!

14.1 What is DAT?  What is its status today?
    DAT (Digital Audio Tape) is currently the standard professional
    digital format for 2-track digital recording.  DAT had a
    short-lived consumer presence, but never "made it".  As digital
    recorders have no tolerance for clipping, using a DAT recorder
    takes a slightly different knack.  The results can be worth it,
    however, as DAT format offers the same resolution and dynamic
    range as CDs.  DATs record for up to 2 hours on a tape, and can
    run at three different sampling rates:  32 kHz, 44.1 kHz
    (for CD), and 48 kHz (the DAT standard).

14.2 What is DCC?  What is its status today?
    DCC is Philips' attempt to modernize the regular cassette.  DCC
    decks can play analog cassettes, and can record new Digital
    Compact Cassettes.  They use stationary heads (DATs use rotary
    heads as do VCR's), and although they are digital, they use
    lossy compression to fit all the data on the cassette.  Although
    DCC sound quality is far better than the 1960 standard cassette,
    the DCC does not have the sound quality present in DAT or CD.
    DCC may be a good choice for consumers who want to assemble mix
    tapes for cars or walkmans, but is not suitable for any
    professional applications.  As of December 1992, DCC is very
    new, DCC equipment is very expensive, and the ultimate future of
    DCC is not assured.

14.3 What about writable compact discs?  What is the status today?
    Recordable CD's are available, but are very expensive.  Blank
    discs sell for approximately $35 each, and the recorders start
    at around $6,000.  These units are mostly used by recording
    studios and other audio professionals.

14.4 What is the best cassette deck under $200?


14.5 What is the best cassette deck under $400?

14.6 What is PASC?  Can I hear the effects?

14.7 What is SCMS?  Can I hear the effects?
    SCMS (Serial Copy Management System) is a copy-protection system
    intended to stop rampant piracy of commercial recordings to
    digital tape.  SCMS allows the home taper to copy from a CD to a
    digital tape, but prevents anyone from digitally copying that
    new digital tape.

    You CANNOT hear SCMS.

14.8 How can I bypass SCMS?
    There are professional devices used by engineers to manipulate
    the digital bitstream, but they cost several hundred dollars and
    are not cost effective for consumers.  If you need to make
    perfect digital copies of digital copies, buy a professional
    digital recorder.  Pro models do not have SCMS, are more durable
    than consumer recorders, and may have better quality electronics
    than consumer models.

14.9 What's this about a tax on DAT?
    Every digital audio tape recorder and every blank digital tape
    sold in the USA is priced to include a "premium" or "tax".  This
    tax is collected by the US Copyright Office and distributed to
    the recording artists and record companies that own the
    copyrights to commercial music.  These fees are supposed to
    repay them for lost royalties.

    Many believe that this "tax" is illegal, because it represents
    an assumption that the buyer will use the recorder and tape to
    violate    a copyright, and not to record their own works.  A
    founding principle of the USA legal system is that everyone is
    assumed innocent until proven guilty.

    If you believe that this law is unjust, write your elected
    representatives.

14.10 Is it legal to copy an LP, CD, or pre-recorded tape?
    In the US today, it may be legal to copy LP's, CD's, etc. for
    your own private use (such as to copy a CD to play on your
    walkman).  UK law specifically prohibits this, but it is almost
    never enforced.  It is definitely not legal in the US, UK, or
    almost anywhere else, to copy these sources for commercial
    purposes, or to give the copies to others.

    It is as of yet unclear whether you own the rights to sell
    or give away a copy of a recording if you made the copy on media
    which was sold with an included digital audio tax.

14.11 How do I clean and demagnetize tape heads?
    First, a caution: DAT recorder tape heads are VERY fragile.
    Before cleaning the heads on a DAT recorder, get specific
    recommendations from a very knowledgeable source that is
    intimately familiar with DAT head cleaning.  In the internet,
    a good source is the DAT-Heads-Digest FAQ.  For more information
    on DAT-Heads-Digest, see section 20.2, below.

    To clean tape heads, use pure isopropyl alcohol and lint-free
    swabs.  Wipe the metal parts of the transport with alcohol
    (DON'T wipe the rollers!) and allow them to dry.  Throw the swab
    away after use.  Be exceedingly careful when cleaning the heads
    on a DAT.  DAT heads are notoriously easy to misalign by
    incorrect cleaning.

    Practical tape head demagnetizers are available for under $10.
    Try to find one with a plastic coated tip.  If you can't find
    one which is plastic coated. you can slip a drinking straw or
    plastic tube over the tip for the same effect.  This plastic
    will prevent the demagnetizer from scratching the head.

    Before plugging in the demagnetizer, remove all tapes from your
    working area and unplug the recorder.  Hold the demagnetizer
    away from the recorder as you plug it in.  Slowly bring the tip
    of the demagnetizer up to the tape head and slide it back and
    forth across each tape head for five one-second strokes.  Then
    pull it away from the head slowly and go on to the next.  After
    demagnetizing the heads, use the tip on each metal tape guide
    with a similar five strokes.  Last, slowly pull the demagnetizer
    far away from the recorder and unplug it.  Recording engineers
    use a demagnetizer before each recording session.

14.12 How do I adjust a tape recorder for best results?
    Adjusting a tape machine for best results usually requires
    special equipment and test tapes.  Unless you know what you're
    doing, leave it for a pro.  If you are serious about doing it,
    buy the service manual for your particular tape recorder.  It
    will list a detailed procedure, as well as describe the correct
    test tape and tools.

    As for setting of record levels, it is best to experiment with
    different levels on different tape brands.  Different
    formulation will reach saturation for different levels.
    Generally speaking, the transients on a Chrome tape should peak
    at about +6 dB above 0, though some formulations can take
    significantly hotter signals.

14.13 Where can I get new pinch rollers or drive belts?
        Projector-Recorder Belt Company
        Whitewater WI USA
        800-558-9572

14.14 What is a good rubber (pinch) roller cleaner?
    Teac RC-1 available from
        J&R Music World
        59-50 Queens-Midtown Expressway
        Maspeth NY 11378-9896 USA
        800-221-8180 or 718-417-3737
    Tascam Rubber Cleaner RC-2 available from:
        Tape Warehouse
        Chamblee GA
        1-404-458-1679

14.15 How can I program a recorder to tape a radio broadcast?
    Radio Shack and Panasonic make a clock/radio/cassette that can
    be set to record at a specific time.  Radio Shack also sells 120
    minute cassettes, which can be used for 60 minutes per side.
    The recorders are not high quality, and the long tapes are
    fragile, but it works.

    You can buy "appliance timers" at hardware stores that will
    start and stop an appliance at a specific time.  Radio Shack
    sells fancier versions of the same thing for more money. Gadget
    freaks love "X-10" control systems.  These can be configured to
    do the same thing.  All require a recorder that can be left in
    RECORD mode.  Such recorders are identified by a "TIMER" switch
    on the front panel.  Many cassette decks have a TIMER switch for
    use with timers.

    Memorex sells a "CP-8 Universal Remote" with a built-in timer.
    Available for approximately $90.00 from either:
        Crutchfield
        1 Crutchfield Park
        Charlottesville VA  22906 USA
        800-955-3000 or 804-973-1811
            or
        J&R Music World
        59-50 Queens-Midtown Expressway
        Maspeth NY 11378-9896 USA
        800-221-8180 or 718-417-3737

    This can be set to start a recorder at a particular time.  As
    the recorder will be started from a remote control rather than
    by the power line voltage, no timer switch is required. Radio
    Shack has a very similar product available for $99.95, may be
    less on sale.

    Damark also sells a learning remote with a built in on/off
    timer and sleep timer. It can learn 17 commands per device on a
    total of 5 devices and should be great for taping a few shows.
    They also sell a 8 device remote with timer.  As Damark sells
    closeouts, these items may not be available in the future.
        Damark
        7101 Winnetka Avenue North
        PO Box 29900
        Minneapolis MN  55429-0900 USA
        800-729-9000 or 612-531-0066

    Use a VCR for audio-only recording.  Hook the audio in to the
    output of a radio, tuner, or receiver.  You may also have to
    connect some video signal to the VCR so that the sync circuits
    work correctly.

14.16 Will CrO2 or Metal tapes damage a deck made for normal tape?
    No.  They will work fine.  They are no more abrasive than common
    tape and may actually be less abrasive than very cheap tapes.
    Recorders which are designed for CrO2 or Metal tape have
    different bias settings and equalization settings to take best
    advantage of the greater headroom and to give flat response with
    these different types of tape.  However, they use similar if not
    identical heads as less expensive tape recorders.  Almost all
    tapes are in some way lubricated, and these lubricants minimize
    wear and squeaking.

14.17 Why do my old tapes squeak in my car cassette deck?
    One problem that will cause this is "binder ooze".  The binder
    is the glue which holds the oxide particles to the backing.
    With time, this binder can ooze forward and actually get past
    the oxide particles, so that there is sticky stuff on the
    surface of the tape.  When this sticky stuff goes past the
    heads, it can cause a slight stick, which will sound like a
    squeak.  You won't feel it with your fingers, but it is there.
    If you have a prized tape with this problem, consider baking
    the tape in a home oven at a very low temperature, like 150F.
    This might cure the problem by drying out the binder.

14.18 Is VHS Hi-Fi sound perfect?  Is Beta Hi-Fi sound perfect?
    The HiFi recording format is subject to two different problems:

    Head-switching noise and compression errors.

    To get perfect reproduction, the FM subcarrier waveform being
    played back by one audio head must perfectly match the waveform
    from the other head at the point of head switching if a glitch
    is to be avoided.  If you record and then play the tape on the
    same VCR under exactly the same conditions, you have a
    reasonable chance of this working.  But if the tape stretches
    just a bit, or you play it on another VCR whose heads are not in
    exactly the same position, or the tracking is off, the waveforms
    will no longer match exactly, and you will get a glitch in the
    recovered waveform every time the heads switch.  This sounds
    like a 60 Hz buzz in the audio, which is often audible through
    headphones even if not through speakers.

    The same glitch will occur in the video waveform too, but since
    head switching always happens during vertical retrace, you won't
    see it.

    The wonderful signal to noise ratio of VHS HiFi is achieved
    through the use of compression before recording and expansion
    after playback.  The actual signal to noise ratio of the tape
    itself is about 35 dB and a 2.5:1 compressor is used to
    "squeeze" things to fit.  Like all companders, this produces
    audible errors at certain places on certain signals, such as
    noise "tails" immediately after the end of particularly loud
    passages.

    Worse, compressors often have problems simply getting levels
    right.  That is, if you record a series of tones, starting at
    -90 dB and working up in 1 dB increments to 0 dB, and then play
    them back, you will almost invariably have level errors.  The
    trend from soft to loud will be there but the steps won't be
    accurate.  Two or three of your tones might come out at
    essentially the same level, then the next one takes a big jump
    to catch up or even overshoot.

    For music, the result will be that the relative levels of some
    instruments, passages, etc. will not be accurate.

    This doesn't matter as much for movies, which tend to have
    steady volume level.  Also, movie enjoyment is rarely hurt by
    these level errors.  VHS and Beta HiFi is fine for reproduction
    of movie and tv soundtracks.  They are also perfectly fine for
    non-critical audio applications.  But VHS and Beta HiFi are not
    serious competitors to DAT, CD, open-reel analog tape, or even a
    high quality cassette deck.

14.19 How do HiFi VCRs compare to cassette recorders?  DAT recorders?
    VHS HiFi and Beta HiFi are analog recording formats which use
    modulation techniques to record a video signal and a stereo
    audio signal on a videocassette.  The audio capabilities
    typically surpass that of the "linear" audio tracks found on all
    video recorders, thus the "HiFi" designation.  "HiFi" is
    essential for getting good sound quality on your video
    recordings and out of pre-recorded videos.

    HiFi is also touted as an excellent audio recorder for
    audio-only (no picture) applications.  On paper, the
    specifications are typically superior to analog cassette but
    inferior to DAT.  In reality, the quality of HiFi video
    recorders is better than low quality cassette recorders but not
    as good as high quality cassette recorders when they are used
    with noise reduction systems.  In no case can a HiFi video
    recorder compare to DAT.  It suffers from generational loss and
    audible noise.

    Many people use VHS HiFi for recording radio broadcasts, since
    VCRs often have built-in timers and can record for up to 9
    hours.  If you use a HiFi video recorder to record from an
    audio-only source, beware that some decks will not function
    properly without a video signal for synchronization.  If you are
    interested in very good quality sound, use a deck with manual
    level control.

14.20 What is the difference between VHS HiFi and Beta HiFi?
    VHS HiFi uses "depth modulation"; Beta HiFi uses "frequency
    modulation".

14.21 Is there any good reason to buy a HiFi VCR for common TV shows?
    If you do not own a stereo TV, the purchase of a HiFi VCR will
    give you the capability to listen to stereo TV broadcasts to
    your system.

| 14.22 What is the best cassette tape?
|    One simple answer to this question is that the best tape is the
|    tape which was used to align your tape recorder.  A second
|    simple answer is that more expensive tapes are frequently
|    better in terms of quality of the backing, durability of the
|    oxide, accuracy of the shell and guides, and life.
|
|    Background: When you make a tape recorder, you build electronic
|    circuits which have specific, non-flat frequency response.  These
|    circuits correct for the non-flat response of the tape heads,
|    the recording process, and the tape.  These circuits can be
|    adjusted after the recorder is made, but adjustment is tricky,
|    and may or may not be successful with every tape made.  The
|    designer of the tape recorder picked one tape as their standard
|    when they did the design, and built that recorder to work well
|    with that particular tape.  It may work better with a different
|    tape, but it won't necessarily sound the best with what one
|    person calls the best sounding tape.
|
|    From a review of frequently given answers to this question,
|    it is obvious that almost every brand of tape has its advocates.
|    Many brands also have their detractors.  Maxell and TDK tend to
|    have a strong following, but that is in part because they own a
|    large share of the US tape distribution market.
|
| 14.23 What is the best Reel-to-Reel tape?
|    See 14.22.  Just as cassette tape recorders are set up
|    specifically for one type of tape, reel-to-reel tape recorders
|    are equalized and biased so that they are best with one specific
|    brand and model of tape.  Just as more expensive cassette tapes
|    will last longer and have less noise than cheaper ones, you can
|    expect fewer dropouts, better quality control, and lower noise
|    from more expensive reel-to-reel tapes.
|
|    The major brands in reel-to-reel tape include Ampex, Scotch
|    (3M), AGFA/BASF, and Maxell.
|
| 14.24 What is Type I, Type II, Type III, and Type IV cassette tape?

15.0 Mail Order
    Mail order is appealing.  The general hope is that by using mail
    order, you avoid pushy sales people, you pay fixed, discounted
    prices, and you have written catalog descriptions to help you
    select your purchase.  In practice, most mail order today is
    "phone order", in that the company completes the deal with a
    phone call.  Many of the "mail order" companies don't even have
    price lists or catalogs.  They are just retailers that are
    willing to sell over the phone and ship the merchandise to
    you.  In some cases, retail store sales are better deals than
    mail order.  Don't expect the lowest price from the first place
    you call.  Also, don't expect excellent service from everyone,
    and especially not from the company with the lowest price.

15.1 Who sells brand XXX equipment mail-order?
    Consult the frequent rec.audio mail-order survey published by
    [e-mail] (William R. Nau) or contact William Nau directly.
|    This survey is also available via FTP in the pub/rec.audio
|    directory of SSESCO.com.  If you have any mail order
|    experiences to share, please send them directly to William Nau.

15.2 Is the stuff sold by DAK really awesome?  Damark?
    DAK buys in large quantities.  They buy what they think
    they can sell.  They buy close-outs as well as new first-line
    merchandise.  They honestly represent their merchandise with
    specifications.  They offer more information on their product,
    if possible, on the phone through their toll free number.
    I know of many people who have bought from DAK and been
    happy. I personally have bought from DAK and been happy.

    Regarding Damark, opinions of people on the net are similar.
    The products are as described, they deliver what they
    say they will, and will take back or replace unsatisfactory
    merchandise.  I have not heard any unsatisfied Damark customers.

    On the other side, the catalog writers at DAK use some very
    flowery language which is intended to lead you to believe
    that they are selling gold for copper prices. In this sense,
    the words in their catalog may be deceptive.

    The DAK people have a good sense of "what the market will bear".
    They price their products to sell, but not to give away money.
    Mail order prices tend to be 10% to 20% less than discount,
    which is 10% to 20% less than retail. DAK has to compete with
    other mail order dealers, such as Damark, but they send out SO
    MANY CATALOGS that they really don't have to cut prices too far
    to sell.

    DAK has recently gone through hard financial times.  This puts
    buyers in some slight risk, because if they go out of business,
    you may get easy warranty service on their products.  I say
    easy because most DAK products are covered by a manufacturer's
    warranty, and you can often get service from the manufacturer
    as well as from DAK.  I believe that DAK is over their slump,
    but I am not sure.  For more on warranties, see 19.1, below.

15.3 Is the stuff sold by Cambridge Sound Works really awesome?

15.4 What should I watch out for when buying mail order?
    Many of the cautions mentioned in warranties (19.1) apply.
    Look for a store which has been around a long time. Look for
    friends which have dealt with the store and been satisfied.
    Look for a store which does not lie or stretch the truth.

15.5 What is gray market?
    See warranties (19.1), below.


15.6 Are there any good mail-order sources for recordings?
    Noteworthy has a good reputation among net readers as a supplier
    of CDs.  They have a range of discs available centered firmly on
    the mainstream, and are reasonable in price.  Shipping is $3.75
    for 1-5 CDs.  They offer over 14,000 different CD titles.  Their
    offerings are all from US labels.  They give a free catalog and
    also have modem software and catalog on floppy discs for $9.95.
        Noteworthy Music, Inc
        17 Airport Road
        Nashua NH  03063 USA
        800-648-7972 Voice
        603-881-5729 Voice
        603-883-9220 FAX

    BMG and Columbia also sell CDs mail-order, but have a smaller
    list of offerings and higher prices. However, BMG and Columbia
    have interesting deals to entice new customers.  Read the fine
    print before you sign to be sure that they are right for you.
    BMG and Columbia both have promotional offerings to "members"
    which allow you to buy two or three discs for the price
    of one.  These can be very good deals, if you want what they
    have.  Look at their advertisements in common magazines and
    Sunday newspapers for a better idea of what they carry.  They
    list much of their line in their ad.  Don't expect much more.

    Bose Express also sells CDs.  Their reputation so far is very
    knowledgable people, a large collection, and high prices.
|    Their catalog costs $6.00.
|        Bose Express Music
|        The Mountain
|        Framingham MA  01701 USA
|        800-451-2673 or 508-879-1916 Ext. 2008
|
|    Tower Records has a mail order department which also sells CDs.
|    Their classical catalog costs $13.45.  Their other catalog costs
|    $10.45.  Tower is a large retail chain.  Many have bought from
|    their retail outlets happily, but no one has expressed any
|    comments on their mail order service yet.  Contact:
|        Tower Records Mail Order Department
|        692 Broadway
|        New York City, NY 10012  USA
|        800-648-4844 or 800-522-5445

    Another source is Music New Hampshire; 800-234-8458.  They sell
    many $3.79 post-paid sampler CDs and also many independent label
    single-artist discs.  Most single artist discs are $15.00 each.
    Shipping is $3 for 1-3 discs and $5 for 4-up.  Their stuff is
    mostly obscure artists.  They have Rock, Jazz, Classical, Folk,
    Country, and Children's offerings.  Affiliated with CD Review.
        Music New Hampshire - Wayne Green Inc
        70 Route 202N
        Peterborough NH  03458-1107 USA

    If you like the idea of buying CDs by Modem, consider
        The Compact Disc Connection
        1016 East El Camino #322
        Sunnyvale CA  94087 USA
        Voice 408-733-0801
        Modem 212-532-4045 New York City NY
              312-477-3518 Chicago IL
              408-730-9015 Sunnyvale CA
              510-843-1259 Berkeley CA
    They have a collection of over 58,000 CD titles.  People have
    said that their service is excellent.  Prices are fairly good.
    Shipping is $3.50 for orders under $100.00 and free for larger
    orders.  They do not stock anything, but deliver from the
    warehouses of their suppliers.  This means that some items may
    be back ordered or completely discontinued while remaining in
    their on-line data base.  They advertise 94.2% of orders in
|    1992 shipped, though not necessarily immediately.  If you have
|    a modem and enjoy browsing a data base, their data base is a
|    a very enjoyable experience.  However, the phone bill can be
|    quite prohibitive to those calling from out-of-town.

    There have been a couple of music (cd/lp) mailorder lists
    compiled on the net - one older list can be found via anonymous
    ftp to ftp.uwp.edu in the file: /pub/music/misc.mailorder.rmm
    Someone is revising this file and it should be updated or found
    in a new file name there in the future.

    Another list contains vendors that specialize in progrssive
    rock, electronic and experimental music, is maintained by
    Malcolm Humes and posted sporadically to alt.music.progressive,
    rec.music.misc, & rec.music.info.  This also can be ftp'd from
    ft.uwp.edu, in the file: /pub/music/misc/mailorder.progressive

|    Federal Music and Video markets "Discount Coupon Books"
|    featuring two-for-one CDs and Tape deals.  They require payment
|    with the order, which many consider risky.  One company that
|    distributes these coupon books for Federal Music is Reed Music.
|    The price from Federal or Reed Music with the two-for-one deal
|    is comparable to the price from Noteworthy.  So far, no net
|    user has yet related any positive or negative experience with
|    Reed Music or Federal Music and Video.  Federal Music and Video
|    has been in business since 1985, so is probably legit. However,
|    in that they require payment in advance it is probably safer to
|    avoid them completely and use a discounter like Noteworthy.

    When considering mail purchases of CDs, consider shipping costs.
    It is common for people to charge between $1 and $3 per disk for
    "shipping and handling".  This makes mail order less attractive,
    but may be equally balanced by a lack of sales tax.

16.0 Wire
    More than any other topic, speaker cables and equipment
    interconnects seem to use up rec.audio bandwidth echoing the
    same theoretical arguments, testimonials, and opinions.
    Controversy can be stimulating, educational, and also amusing.
    Please try to keep postings aimed at one of those three goals,
    and avoid the insults and emotion.  Also, try to avoid
    echoing a common position or principle, as described below.

16.1 Do speaker cables matter?
    To avoid confusion and repetition, here is some terminology.
    Cables are connectors attached to wires. Wires generally
    have multiple conductors optionally surrounded by a shield and
    outer insulating covering. Cables can introduce noise into the
    signal, act as a filter (and thus change the frequency response
    of the system), and provide nonlinearities from improper
    (intermittent/loose) connections to or between the connectors.

    It is quite scientifically conceivable that some cables do cause
    a difference in sound, because of the differences in DC
    resistance, interconductor capacitance, and connector attachment
    alone.  The effects of exotic conductor weaving and materials
    are not so well established.  In general, these effects (once we
    eliminate DC resistance), seem to be small. However, if your
    system is at least fairly good, then some folks have observed
    (although not in an experimental, double-blind sense)
    significant differences in system performance with different
    cables. The effects are said to be quite system specific; the
    only real guideline is to try them and see which ones seem to
    sound better in your system.

    Roughly speaking, the price ranges for speaker cables is low
    (under $1/ft), medium (under $6-8/ft), and high (up to $100/ft
    and more). Try to arrange it so you can trial such cables; at
    several hundred dollars per set, experiments can be expensive.

    In any system or experiment, it is essential that the
    differences between cables be separated from the differences
    between connectors.

    You should have an EXTREMELY solid connection between cable and
    speaker.  Speakers operate at very low impedances, so that bad
    connections will create significant artifacts or signal losses
    at any power level.  For example, if the connection has a linear
    resistance of just 1 ohm, the speaker damping factor will be
    dramatically reduced, making bass muddy.  If the connection
    contains imperfect metal oxides, then a slightly rectifying
    junction will block the signal, producing compression,
    distortion, and other non-linear effects.

16.2 What speaker cables are available and how good are they?
    There is a wide range of speaker wire available, ranging from
    30ga zip cord (~$.10/ft) to exotic wires costing over $300/ft.
    The material used ranges from copper to oxygen-free copper (OFC)
    to silver. (There are a bunch of others as well.)

16.3 What can I use for budget speaker cables?
    First, a few words on terminology.  Wire is sized by AWG or BS
    gauge number.  Larger numbers represent smaller wire.  AWG 40
    (also called 40 gauge) is as fine as human hair.  AWG 12 is 2mm
    or .081" diameter.  Some wire is classified as solid, because it
    contains one strand per conductor.  Other wire is called
    stranded, because it consists of many strands per conductor.
    Stranded wire is far more flexible than solid wire.  Most wire
    is made from drawn copper.  Some wire is sold that is claimed to
    be made with a process that produces oxygen-free copper.
    Oxygen-free copper has a different metallurgical structure than
    common copper and may or may not conduct current better.

    Some critical listeners have reported excellent sound from large
    diameter solid copper wire, such as home wiring "Romex 12-2".
    At least one expert has said that common 18-gauge solid copper
    hook-up wire sold by Radio Shack also works very well.  Also
    recommended on a budget is Sound King wire, a 12 gauge oxygen
    free copper stranded cable.  This is available from MCM
    Electronics for $.39/ft.

    The scientific literature indicates that small gauge wire
    generally sounds worse than large gauge.  Resistance-related
    effects of the cable can be eliminated by using at least 12
    gauge wire, particularly for long runs.  Of course, shorter runs
    are always preferred, because they come much closer to the ideal
    zero-length wire, with no resistance, no capacitance, no
    inductance, and no change in signal.
--
Bob Neidorff; Unitrode I. C. Corp.  |  Internet: [e-mail]
7 Continental Blvd.                 |  Voice   : (US) 603-424-2410

=========================================================================
·    Subject: rec.audio FAQ (part 4 of 4)

Archive-name: AudioFAQ/part4
Last-modified: 1993/3/8
Version: 1.2

16.4 What can I use for budget speaker connectors?
    The worst connectors are push-down, or spring terminals.  Screw
    terminals with solid copper wire are much better.  Gold-plated
    binding posts and gold spade lugs are inexpensive by audiophile
    standards and are extremely stable.  Binding posts with spade
    lugs can be tightened to get a very good mechanical joint, and
    may offer the lowest electrical resistance of any connector.

    Gold plated banana plugs and jacks are very good speaker
    terminals.  Good ones are more expensive than gold spade lugs,
    however, they also provide a bigger area of contact, and are
    more convenient when you must frequently reconfigure the system.
    Banana plugs should be periodically monitored for corrosion and
    loss of spring tension.  Monster offers a banana-plug connector
    with an expanding center pin that forms an even better
    connection than common gold banana plugs.  At approximately $25
    per pair, the Monster banana plugs aren't a budget connector.

    All else equal, connectors with gold surfaces are better than
    connectors with any other surface.  This is for two reasons.
    First, gold is extremely inert, meaning that unless gold is
    exposed to very harsh chemicals or harsh vapors, it will not
    corrode or oxidize.  It will remain a pure, low-resistance
    conductor.  Second, gold is quite soft, so that if a gold-plated
    connector is squeezed between two metal surfaces, it will deform
    slightly to fill scratches and voids, giving a very broad,
    low-resistance contact area.

    Corrosion of connectors is often a problem.  Gold-plated
    terminals and connectors somewhat avoid this problem; problems
    with other connectors can be mitigated by unplugging and
    replugging the connector on a regular basis, cleaning the
    contact areas with a pencil eraser, or by using a contact
    enhancer such as Cramolin or Tweek.  When you use a contact
    enhancer, be very sure to follow the directions, and avoid
    spreading enhancer about your equipment.

16.5 What about interconnects, such as the cable between tuner and amp?
    Line-level interconnects conduct smaller signals than speaker
    cables; the typical signal ranges from -2V to +2V (the CD
    output standard) with currents in the microamps (the
    corresponding values for speaker cables attached to a largish
    power amp might be -70V to +70V and currents of many amps).
    Line-level interconnects can be divided into single-ended (or
    unbalanced), and balanced interconnects.  Home audio is almost
    always single-ended interconnects.

    Single-ended interconnects almost always use a form of the RCA
    connector (or phono plug). RCA plugs form fair to poor
    connections that degrade with time as corrosion works into the
    metal-metal contact and as the spring tension of the connectors
    relax.  Gold-plating reduces the effect of corrosion and locking
    RCA connectors solve most of the mechanical problems.  However,
    these premium phono connectors are rare and expensive.  For
    example, a gold-plated Vampire locking RCA plug costs
    approximately $23/pair.  If RCA connectors weren't a de facto
    standard, we'd recommend against them.

    Unbalanced interconnect wires vary in geometry, material and
    price.  Cheaper wires have a single conductor (normally
    stranded) and a shield and cost $.20-$2/ft. Medium (complexity
    and price) wires have two conductors (often arranged as a
    twisted pair) surrounded by a shield and cost from about
    $3-$20/ft.  Exotic wires have all sorts of geometries and
    materials (such as stranded silver conductors, or ribbon cable
    braided around a core, or in one extreme case, a tube filled
    with mercury!).  Prices may be as high as $200-$300/ft.

    Balanced interconnects have three conductors: two for the signal
    one for ground, and additionally a shield.  The standard
    connector for balanced cable is the ITT/Cannon XLR connector,
    which is quite good mechanically (they lock).  Equivalent
    connectors are also available from Switchcraft, Neutrik, and
    other vendors.  If you have to run cables longer than 12 feet or
    4 meters, the greater noise immunity of balanced interconnects
    is often a good idea. For this reason, balanced connectors are
    standard equipment in professional installations such as
    studios, public address systems, and broadcast stations.  There
    is not much variation in balanced cables.  The three brands
    mentioned above are known to be rugged, high quality and
    moderately priced. Slightly weaker imported connectors are
    available, but they aren't dramatically cheaper.

    For most systems, the most important aspect of a cable are
    the mechanical reliability of the connectors; in particular,
    the joint between connector and wire, and the joint between
    connector and socket. Typically, interconnect cables are
    short.  It is worth getting just the right length; cables
    often come in .5 meter increments.  With quite good systems,
    some people observe differences in sound between various
    interconnects. This is quite system-specific and the same
    advice as given above applies: try several brands.  Most
    good dealers will loan interconnects for home evaluation.

    In cables where the shield does not carry the signal or ground,
    the shield is normally only connected to ground at one end.
    In systems where there are significant differences between
    ground levels on various components, it may make a difference
    which way such cables are connected.  Typically, the end where
    the shield is grounded should be at the source of the signal.
    Often, such cable has arrows on it pointing in the direction of
    the signal flow.  In any case, try both orientations.

    There are many objective reasons why cables might cause
    differences in sound by interacting with the drivers in the
    signal sources as well as by providing non-linear effects in the
    RCA connector.  Most of these effects are again related to
    interconductor capacitance and resistance, and the quality of
    the shielding provided by the "shield" conductor.  In balanced
    cables the quality of the "twisted pair" inside the shield is
    also important.  One might note that a shield protects from only
    capacitively coupled interference, and not from any magnetic
    field interference.  The twisted pair in a balanced line provide
    some magnetic rejection, as does steel conduit.  However, steel
    conduit has other characteristics which make it undesirable for
    audio in general.

16.6 What about Phono Interconnects:
    Phono interconnects are part of the link between a cartridge on
    a turntable and a preamp (or head amp or receiver). They are a
    special case of line-level interconnects because the signal is
    much lower, typically 1 to 50 millivolts.  They are also
    intended to operate into a higher impedance, typically 47K ohms,
    and form part of the capacitive load for the cartridge.

    The low signal levels mean that the shielding of the cable, and
    the presence of a separate drain/shield are more important, as
    is a good ground.  A separate solid ground should come along
    with the cable as a separate lead co-routed with the cable.

    In addition, the low signal levels make a good solid connection
    to and through the connectors MUCH more important, because of
    the greater sensitivity to low-level nonlinearities.

    Wire capacitance is often ignored in line-level interconnects;
    however, in a phono interconnect, it may constitute half of the
    total capacitive load of the cartridge. Obviously, then, two
    cables with significantly different capacitances should sound
    differently.  In this sense, the "right" cable for one cartridge
    may be too low or high in capacitance for another cartridge.

    For low-impedance cartridges (most moving coil cartridges),
    the wire must have low resistance to prevent cartridge unloading
    and frequency-dependent signal loss. In addition, as the
    signal levels are quite low, shielding is important.

    Unfortunately, copper shields do not block stray magnetic
    fields, so in the case of phono cables, careful routing may be
    even more effective at reducing hum than special wire.

16.7 Is there really a difference in digital interconnects?
    There are now three kinds of digital interconnects that connect
    transports to D/A converters: coax, plastic fiber (Toslink) and
    glass fiber (AT&T ST).  In theory, these should sound EXACTLY
    the same (bits are bits).  However, this assumes good circuit
    design (in particular, the clock recovery circuits of the DAC,
    and careful consideration of electronic noise) which may be
    compromised because of cost considerations or ignorance.  Note:
    different signaling schemes are used on plastic and glass fiber.

    In any case, some people claim to hear a difference; of those
    who do, most seem to prefer the glass fiber.  However, the
    technology of fast digital data transmission in consumer
    electronics is evolving very quickly now.  Any specific
    recommendation should be treated with suspicion until the
    industry matures.

16.8 Can I make very good interconnects myself?
    Yes.  You will need to be the judge of whether or not they
    are as good as $100 interconnects, but it is easy to make
    interconnects that are better than the $2.00 set which comes
    with new equipment.

    There are two necessary ingredients: two-conductor shielded
    cable and RCA connectors.  There is a lot of debate over what
    is the best cable, but in general, the lower the capacitance
    per foot, the better.  Choice of insulation is harder.  There
    may be an advantage to polypropylene or teflon over polyester
    or rubber, but even that is debatable.  If you are buying wire
    from an electronics distributor, some have successfully used
    Belden 1192A microphone cable.  It is rubber insulated, so very
    flexible.  Another recommended cable is Belden 8451.  This is
    a polypropylene cable with foil shield.  Finally, consider
    Belden 89182.  This is foamed teflon insulated, so very low
    capacitance, and foil shielded.  If you plan to make a long
    cable, this low capacitance cable may be the best choice.


    There is also a variety of RCA connectors available.  A good
    connector would be gold plated and machined to tight tolerances.
    A poorer connector will not fit as well, will make poorer
    contact as the connecting surface oxides, and will lose its
    springiness with use.

    When wiring the cable to the connector, use one wire for signal,
    (the tip of the RCA connector) and one wire for ground (the
    shell or outer conductor of the RCA connector).

    Some cables use a foil shield which is difficult to solder.
    These cables typically have a drain wire parallel to the foil
    which can be used for soldering.  Others use a braided shield.

    Regardless of which type of wire you have, connect the shield
    or the shield drain wire to ground on only ONE SIDE.  This will
    stop noise picked up by the shield from causing ground noise.

    It can be a fiddly job soldering RCA connectors.  Before you use
    your new cables, check with an ohmmeter or a continuity tester
    to make sure that you have not accidentally sorted the signal
    and ground leads together, either with a stray drop of solder or
    a loose wire strand.

17.0 The Press

17.1 Which magazine should I read?
    Which ever one you like.  None are absolutely objective.
    Here's a list of some common ones:

        Audio Magazine (US $24/year 12 issues.  Mid-fi)
            PO Box 53548
            Boulder CO  80321-2548 USA
            800-274-8808, 303-447-9330
        Audio Critic (US $24/yr 4 issues) (High-end)
            PO Box 978
            Quakertown PA  18951 USA
            215-538-9555
        Audiophile (High-end, High-$$$ Buying Guide,
                Blind reviews)
            Haymarket Trade & Leisure Publications Ltd
            38-42 Hampton Road
            Teddington, Middlesex, TW11 0JE,  UK
            [phone]
            US Inquiries should go to:
                Eric Walter Associates
                Box 188
                Berkeley Hts NJ  07922 USA
                201-665-7811
        Car Audio and Electronics ($19.95/year 12 issues)
            Avcom Publishing Ltd
            21700 Oxnard Street
            Suite 1600
            Woodland Hills CA  91367 USA
            818-593-3900
        CD Review (Music Reviews; all tastes, only CDs.)
            $19.97 per year 12 issues
            PO Box 588
            Mount Morris IL  61054 USA
        Hi-Fi Choice (Mid-end. Comparative reviews with graphs,
                tables, and subjective commentary;
                'Buying Guide' section)
            Dennis Publishing Ltd.
            14 Rathbone Place
            London, W1P 1DE, UK
            [phone]
        Hi-Fi News and Record Review (Mid-end. Good new record
                reviews)
            Subscriptions Department
            Link House Magazines Ltd
            1st Floor
            Stephenson House, Brunel Centre
            Bletchley, Milton Keynes MK2 2EW, UK
        HiFi Heretic
            PO Box 2019
            Yorba Linda CA  92686 USA
        Hi-Fi World  (Friendly, lower-mid-end magazine)
            (reviews and "how things work" articles)
            Audio Publishing Ltd
            64 Castellain Rd
            Maida Vale
            London  W9 1EX, UK
            [phone]
        In Terms Of Music  (Emphasizes music reviews, new)
            PO Box 268590
            Chicago, IL 60626  USA
            312-262-5918
        International Audio Review
            2449 Dwight Way
            Berkeley CA  94704 USA
        Positive Feedback (Technical articles by big-names)
            Oregon Triode Society
            4106 N.E. Glisan
            Portland OR 97232 USA
        Stereophile (US $35/yr 12 issues) (High-end)
            208 Delgado
            Santa Fe NM  87501 USA
            800-435-0715 or 505-982-2366
        Stereo Review (US $6.97/yr 12 issues.  Lower end/mass
                market)
            PO Box 52033
            Boulder CO  80323-2033 USA
        The Absolute Sound (US $46/yr 8 issues) (High-end)
            Box 6547
            Syracuse NY  13217 USA
            800-825-0061
        The $ensible Sound (Mid and High-end)
            403 Darwin Avenue
            Snyder NY  14226 USA
            716-681-3513
        What Hi-Fi  (Mid-end; comparative, subjective reviews)
                (contains it's own buyer's guide with
                recommendations)
            Haymarket Trade & Leisure Publications Ltd
            38-42 Hampton Road
            Teddington, Middlesex, TW11 0JE, UK
            [phone]
            US Enquiries should go to:
                Eric Walter Associates
                Box 188
                Berkeley Heights NJ  07922 USA
                201-665-7811

17.2 Which reviews are better?
    Some reviews are so colorful and exciting, that they make great
    journalism and fun reading.  Lets ignore these for now,
    even though they have their place.

    Beware of reviews from magazines that advertise the same
    product.  The likelihood of bias is too high. Unfortunately,
    that rules out 99% of the reviews in magazines.

    Stereo Review has a bad reputation for loving everything
    made by every advertiser.  Even high-end journals such
    as Stereophile and The Absolute Sound can be influenced.

    A classic example of misleading reviews occurs with equipment
    submitted to a magazine for review.  The manufacturer may send
    the editors a carefully built, adjusted piece for review.  The
    magazine will honestly rave about it. The manufacturer will then
    send the design off-shore for more economical manufacture and
    assembly, and the quality will suffer.  Lower quality components
    will be substituted for prime parts.  Adjustments will be made
    to wider tolerances or will not be made at all.  The design may
    be completely changed to make it more manufacturable.  You will
    unknowingly get a completely different piece than reviewed.

    Home auditions with one or two candidates from each of a few
    dealers are your best guide to be sure that you get what you
    want and pay for.

17.3 Is Consumer Reports right?
    Consumer Reports is the most objective testing lab we have ever
    found.  Unfortunately, they are also the world's least
    specialized testing lab.  They market their testing to the
    average consumer.  The average consumer will not hear some of
    the subtle differences which audiophiles hear.  For that reason,
    Consumer Reports ignores issues that others feel vital.

    Consumer Reports also insists on basing their audio testing
    predominantly on lab measurements.  Although lab measurements do
    tell many differences between devices, interpreting lab
    measurements for best sound is difficult or impossible.  For
    example, it is very hard to compare two speaker frequency
    response curves and tell which will sound better.  Some $3000
    speaker frequency response curves look worse than some $600
    speaker curves, even when tested in the same setup.  On the
    other side of the issue, Consumer Reports has improved its test
    methods, and will continue to improve.  Expect the accuracy of
    their reviews to improve with time.

    The Consumer Reports frequency-of-repair data base is larger
    than any similar data base published and can be trusted as well
    as any statistic.

18.0 Retail

18.1 Should I use an up-scale retail store?
    This is probably the best place to listen to gear in a
    controlled environment, next to your home.  This is the best
    place to find expensive, high quality gear.  This is the place
    which is most likely to have a good policy on home trials and a
    liberal return/upgrade policy.  This is also likely to be the
    most expensive place to shop.  One exception to this is that
    these stores have the ability to sell demos, returns, and
    discontinued gear at very advantageous prices.

    Some up-scale dealers will negotiate price on large systems or
    expensive purchases.  It never hurts to ask.


    There are definitely better and worse local hi-fi stores.  If
    you find a really good one, it is probably worth the extra money
    to buy from them, rather than from discounters.  A really good
    store will not push you to buy what they want to sell.  A really
    good store will allow you to take your time with your decision.
    A really good store will not distort the truth in describing
    equipment.  A really good store will help you get the most out
    of your purchase by showing you how to set it up.  They will
    tell you what placement works best for the speakers.  (Don't
    believe them if they tell you to put them anywhere.)  A really
    good store also selects their lines carefully.  They don't want
    dissatisfied customers or warranty returns any more than you do.

    Due to the nature of the customer, a hi-fi store in a shopping
    mall is likely to use high-pressure sales techniques.  They know
    that the majority of their customers are distracted easily by
    299 other stores.  Most of their sales go to customers that come
    in for 3 minutes, select something, and leave.  There are
    exceptions to this, of course, but if there was a good
    generalization, it would be to look elsewhere.  There are stores
    in large buildings, small buildings, private homes, shopping
    plazas, and every other conceivable venue.  Search from among
    these to find one that meets your needs and fits your style.

18.2 Should I use a discount store?
    If you need to listen carefully before making up your mind,
    discount stores can be very frustrating.  If you know exactly
    what you want, then this can be a great place to save money.
    Don't expect knowledgeable sales help or after-sale support.  Be
    sure to ask about the warranty  (see 19.1 below on warranties).

18.3 Is it right to negotiate price?
    Most people feel that it is fair to negotiate.  Some feel that
    it is fair to lie in negotiating, as the sales people frequently
    lie to you also.  Others think that lying to get a lower price
    is an immoral practice.  It may even be illegal, an act of
    fraud.

    Some people feel that if you negotiate over price, you encourage
    stores to mark prices artificially high, so that the stores have
    room to negotiate.  Others feel that in negotiating, you are
    asking the store to accept a lower profit, or asking the sales
    person to take a lower commission and are directly hurting them.

18.4 How can I negotiate price effectively?
    A great source of information on this topic is available from
    books on buying a new or used car.  However, some very helpful
    general tips include:
        Know the competition and the dealer.
        Know the gear.
        Know the prices available elsewhere.
        Believe in your research, not their words.
        Stand your ground.
        Be nice to the people but hard on the deal.
        Be prepared to walk away if they won't agree.
        Expect their lines and prepare responses in advance.
            For example, expect the dealer to claim that the
            Nakamichi deck is the best cassette deck on the
            market.  Be ready with a reply such as at that
            price, you can buy a DAT machine which has
            better frequency response, lower signal to noise
            ratio, etc.

18.5 It sounded great in the store.  Is it great?
    Never let anyone else pick stereo for you.  Especially not
    speakers.  They all sound different, and you don't need a golden
    ear to hear the differences.  Listen for yourself and ignore
    what the sales people say.

    If you are still unsure, ask the sales people to let you take
    the gear home for a home trial in exchange for a large deposit.
    Home auditioning takes 99% of the risk out of store auditions.

18.6 Do sales people try to trick the customer?
    Some do and some don't.  Some will treat unpleasant customers
    badly and treat friendly people well.  Most sales people aren't
    wealthy.  They sell stereo to make a living.  If they can sell
    you a more expensive piece of equipment or a piece of equipment
    with a higher profit, they will make more money.  Usually, this
    figures into everything they say.  Some sales people claim to be
    altruistic.

    Some sales people really are open and honest.  They may starve
    with this approach, or they may have a nice enough personality,
    a good enough product line, a good enough store behind them, or
    enough technical background to overcome this "limitation".

18.7 How can sales people trick the customer?
    Often, a customer will trick him or herself without help.  We
    are often swayed by appearance, sales literature, position of
    the equipment in the show room, and our own desire to buy what
    others will like.

    Some times, the sales person will actively try to push a
    particular piece of equipment by demonstrating it against
    another piece of equipment which is inferior or defective.

    Some sales people will demonstrate a set of speakers while
    simultaneously driving a subwoofer, even though they are not
    telling you this.  With the subwoofer, it probably will sound
    better.

    Some sales people will demonstrate one set of speakers louder
    than others.  Louder almost always sounds better.

    Most stereo buyers go into the store, spend a few minutes
    selecting what they want, lay down big bucks, and leave.  They
    don't need to be tricked.  They don't listen carefully.  They
    trust the sales person's choice as best in their price range.
    For non-technical reasons, these people are the most likely to
    be satisfied with their purchase.

18.8 What should I ask the sales person?
    What do you want to know?  Seriously, the best questions are
    those which the sales person can answer without distorting the
    truth.  Don't ask a sales person to compare their brand to a
    brand they don't sell.  Don't ask "how good is the ...".  Ask
    questions of fact.

    Here are some questions you may want to ask:
        If I don't like it can I return it for a full refund?
        Can I try this out at my home in exchange for a deposit?
        What does the warranty cover?  For how long?
        What do I need to know to set this up for best sound?
        Do I get a manufacturer's warranty with this?
        Where do I take this to get it repaired under warranty?
        Where do I take this to get it repaired out of warranty?

18.9 How do I impress the sales person?
    Why would you want to?  You have money and he doesn't.

18.10 How do I get the best service from a sales person?
    Be honest with the sales person.  Set some reasonable request
    and ask them to meet it.  For example, say that you will buy
    this if you can try it at home first and listen to it
    side-by-side with a piece from another store.  Alternately, say
    that you saw the same thing at store Z for $xx less, but you
    will buy it from the guy if he will match the price.

19.0 Miscellaneous

19.1 What do I need to know about warranties?
    Warranties have a few basic components.  The first is the term
    of the warranty.  The second is what is covered.  The third is
    who supports the warranty. The fourth is what restrictions.

    Term is fairly self evident.  What is covered is more detailed.
    In audio electronics, typically everything is covered with a
    "parts and labor" warranty.  Often mechanical components such as
    tape heads are covered by different terms, such as shorter terms
    on labor and longer terms on parts.  Likewise, speaker
    warranties vary widely, from unconditional with no term limit to
    a basic 30 days parts and labor.

    Some warranties come from the manufacturer.  Others come from
    the dealer.  Still other warranty support is available with
    certain premium charge cards.

    A common restriction on some warranties is that the equipment is
    not covered unless it is sold by an authorized dealer.  A few
    dealers have lied about being authorized dealers.  Equipment
    sold by an unauthorized dealer is almost always sold completely
    legally.  This unauthorized dealer may, in fact, be fully
    authorized to sell, but not authorized to sell manufacturer's
    warranties.  In buying gear this way, dealers can get it
    cheaper, and provide the service themselves.  This kind of gear,
    with a full warranty from the dealer is referred to as gray
    market equipment.  Manufacturers discourage buying from these
    gray market dealers, but the risks are fairly low.  If the
    dealer is local and well established, the risks are minimal.

    If you buy equipment mail-order, a dealer warranty may be a pain
    in the neck, especially if you have to ship the gear to the
    dealer more than once to get it fixed correctly.  Then again,
    some factory service requires shipping gear far away at your
    expense, too.

    Frequently, home audio equipment is sold with a warranty
    restriction that if the gear is used commercially or in any
    profit-making enterprise, then the warranty is void. This is to
    protect the manufacturer from having to frequently repair
    equipment meant for light service.  Professional audio equipment
    often comes with very liberal warranty terms, such as lifetime
    parts and labor.  Professional gear takes heavy use and severe
    wear from constant transportation.  It is expected to be able to
    take this abuse.

    All gear, electronic and mechanical, is known to have three
    principal failure modes: abuse, infant failure, and end-of-life

    failure.  In addition, a few of the failures occur at random.

    Infant failure occurs in the first fifty hours of use, and is
    the principal responsibility of warranties. Infant failure is
    frequently caused by defective parts or a design defect.

    Abuse failure is that caused by a person who pulls a cable too
    hard, bangs the equipment on the table, pushes the controls too
    firmly or too fast, or does anything else which the manufacturer
    did  not expect. These are the gray areas of warranties.  They
    do not represent a manufacturing defect in the manufacturer's
    eyes, but they do leave you with a broken device.  To get
    the best chance of coverage against this kind of failure, select
    a brand or a dealer with a very liberal warranty policy.

    End-of-life failures are rarely covered by warranty.  Tape heads
    have a finite, calculable life, as do rubber rollers, speakers,
    cables, batteries, bearings, and motors.  The life of some of
    these components can be extended by intelligent care.  For
    example, the life of common rechargeable batteries can be
    extended by good recharging practice.  Likewise, some cleaners
    can dry out rubber, and will lead to premature failure. Don't
    expect warranty support for any of these problems, and if you
    get it, feel lucky.

19.2 What is blind testing?  Non-blind?  Double-blind?  ABX?

19.3 Where can I get a service manual for brand XXX?
    The most reliable source of supply is the manufacturer's sales
    office in your country.

19.4 Where can I get good repairs on brand XXX?

19.5 How can I take 115V gear over to a 230V country or vice versa?
    Some equipment is available with an international power supply,
    which can be rewired by any serviceman to either power line
    voltage.  If you expect to be moving abroad, look for this kind
    of equipment.  Often, the same model is available both as US
    only and as International. Some equipment will be rewirable and
    won't say it.

    If you know that your gear is limited to one power line voltage,
    you can order a new power transformer for that receiver, CD
    player, amplifier, or tuner which will be wound differently.
    Contact the manufacturer's local service center.  This can be
    very expensive.  A new  transformer for a 40 watt receiver would
    wholesale for under $25 but cost $75 from a service center.

    Another alternative is to buy a power transformer that will
    convert 115V to 230V and vice versa.  Here are some common
    models and their list prices.  Note that the power ratings are
    total line current multiplied by line voltage (2A at 115V is 230
    watts).  Larger transformers are available for more money.  Some
    of the costlier transformers are constructed with plugs and
    jacks for immediate use.  Those marked * have wire leads and
    need safe connections to be used.

    Before spending money, check into other things about audio in
    the new country.  Broadcast frequencies are slightly different
    in some countries than in others, so a receiver or tuner bought
    in one country may not be able to receive some or all of the
    stations in another country.  The US separates the AM broadcast
    band frequencies by 10kHz while the UK uses 9kHz.  Similarly,
    the US separates FM stations by 200kHz, where the UK has
    stations on a 50kHz spacing pattern.  It MAY be very simple to
    modify a receiver from US to UK spacings, but may not.

    Step Down (230V in, 115V Out)
        MagneTek/Triad    N1X*    50 Watts    $11.83
        Stancor        P-8620*    50 Watts    $14.16
        MagneTek/Triad    N3M    85 Watts    $29.95
        Stancor        P-8630    85 Watts    $43.65
        MagneTek/Triad    N6U*    200 Watts    $25.72
        Stancor        P-8632    200 Watts    $51.80
        MagneTek/Triad    N5M    250 Watts    $42.60

    Step Up (115V In, 230V Out)
        Stancor        P-8637    85 Watts    $43.10
        MagneTek/Triad    N150MG    150 Watts    $49.46
        MagneTek/Triad    N250MG    250 Watts    $54.69
        Stancor        P-8639    300 Watts    $55.51

    The Stancor and MagneTek Triad lines are carried by
    large electronic distributors.

19.6 Are there really good deals in country XXX?

19.7 How do I find out how much an XXX is worth?
    There is a "Blue Book" for used audio equipment called
    "Orion Blue Book-Audio".  This guide lists both a
    wholesale and a retail value for most audio gear.
        Orion Research Corporation
        1315 Main Avenue Suite 230
        Durango CO  81301 USA
        303-247-8855
    Last I knew a guide costs $150. Each Nov, a new book is printed.
    After August, the old book is discounted. Some rec.audio readers
    have the Orion Blue Book and will look up gear for others.

19.8 Do people really hear those differences?
    Who knows?  They sure think that they do.

19.9 Why do people disagree on what is the best sound?
    There are at least three different measures of what is "Perfect
    Sound".  All three have advocates, and all three are right, in
    their own way.  In general, whether they admit it or not, most
    listeners fit into one of these three preference groups:

    1.    It must sound like live music.  These people know what
        voices sound like in person, they know what instruments
        sound like without any amplification, and they have
        heard orchestras perform unaided by sound systems.  They
        want to accurately reproduce that sound.

    2.    It must sound like the recording engineer wanted it to
        sound.  The recording engineer listened with extremely
        good equipment to the sound coming out of the
        microphones, and mixed them together for what he, at
        that time, felt was artistically correct.  It may not
        have been the same as live, but it was exactly what he
        wanted.  In the extreme, people like John Fogerty used
        to audition his final recording mix in his truck to see
        how it would sound through a common, lousy stereo.

    3.    It must give me the most pleasure.  No matter how good
        or bad live sounds, no matter what the recording
        engineer intended, if buy some equipment will give me
        more listening pleasure then it must be the best.

    With these three perspectives, it is clear that no one system
    will satisfy everyone.  Add to that confusion the variable that
    everyone likes a different kind of sound, has heard live music
    under different conditions, and has a different idea of what the
    engineer intended.  There is an enormous range of possibilities.

    Another set of reasons is that people look for different things
    to be right.  Some want strong bass; others want male voices to
    sound like  male voices; others want violins to sound like
    violins. Systems rarely do everything equally well. Speakers (in
    particular) are compromises.  Look for the speaker where the
    designer had your priority first.  You are perfectly right to
    select speakers based on YOUR personal taste.

    Confounding the situation further, we all say the greatest
    things about the stuff we already bought.  To do otherwise would
    be to admit that we are either stupid or deaf.

    Still another reason is that most people haven't heard enough
    variations.  Until you hear a system that can truly reconstruct
    the three-dimensional accuracy of a stereo image accurately, you
    may never realize that it is possible.  Some excellent
    recordings contain enough information that with a good enough
    system, you can hear up-down, in-out, and left-right
    distinctions very clearly.  However, we will never experience
    this until we are fortunate enough to hear such a fine recording
    on a very good system.

    Finally, some of us really can't hear much difference.  We
    aren't deaf, but we don't have a well trained ear, don't know
    exactly what to listen for, and may even have slight hearing
    deficiencies, such as bad sensitivity to high frequencies which
    comes with older age, or hearing damage from listening to loud
    sounds (machinery, rock concerts, etc).

| 19.10 How do I contact the manufacturer of XXXXX?  How do I get repair
|        service on XXXXX?  How do I get replacement parts?
|    Some magazines publish lists of contact phone numbers for the
|    manufacturers of equipment.  In the US, Consumer Reports has a
|    small listing in each issue and a more comprehensive listing
|    in their March issue.  Also, Audio Magazine has an exhaustive
|    listing in their October "Equipment Directory".  In Europe, look
|    in "What HiFi?".
|
|    You can find many addresses by reading ads in hifi magazines.
|    You can also find out by asking at your friendly local hifi
|    shop, especially if you've built up a relationship with them.
|
|    repair center.  The best way to locate one near you is to look
|    at the literature which came with your equipment when it was
|    new.  Failing that, see the ideas mentioned above in 19.10.

20.0 Network Protocol

20.1 What are the other newsgroups on audio and music?
    rec.audio.pro: This newsgroup is dedicated to professional
        audio.  It includes discussion on record production,
        studios, studio equipment, DJ equipment, recording
        concerts, sound reinforcement, mastering, mixing,
        special effects, and other topics which might apply to

        audio professionals.  If you are a home audio buff but
        like tape recording, you can find good advice here.
    rec.audio.high-end: This newsgroup caters to audiophiles and
        serious music lovers who are interested in discussing
        the subtle differences between expensive equipment, the
        nuances of selecting the best cables, the love and lore
        of LPs, and other details of audio that are inaudible to
        the untrained ear.
    rec.audio.car: This newsgroup supports discussion on different
        brands and models of car stereo, and also is an open
        forum for talk about car stereo installation, speaker
        selection, custom crossovers, and the special noise
        problems which occur in cars.

20.2 What network mailing lists are out there which aren't on usenet?
    There is an informal group of people interested in using DAT
    recorders to record "Grateful Dead" concerts. These people call
    themselves "Dat-Heads" and have a daily E-Mailing List.  To
    subscribe to this list, send a message to:
        [e-mail]
    asking to join the mailing list.

20.3 Should I post a question about "XXXXXXXXXXXXX"?
    If it is related to professional audio, take it to
    "rec.audio.pro".  If it relates to very expensive audio
    equipment or a request for opinions on subtle sound differences,
    you might want to take it to the newsgroup "rec.audio.high-end".
    Otherwise, if it isn't addressed in the FAQ and it isn't a
    question for one individual, do it!

20.4 How can I suggest a change to the FAQ?
    Send an E-Mail message to [e-mail] and explain your
    suggestion or correction in detail.

20.5 Where is the FAQ for rec.audio archived?
    This FAQ is available via ftp.  Assuming you have access to the
    internet, the scenario is approximately:
        ftp research.att.com
            # research's IP address is 192.20.225.2
        <login as anonymous; password is your email address>
        cd dist
        get audio.faq
    If you have problems or need further help with accessing the FAQ
    via internet, send e-mail to
                [e-mail]

20.6 What does FAQ stand for?
    FAQ stands for "Frequently Asked Questions".  It is assumed that
    a FAQ also contains FGA or "Frequently Given Answers".  The
    newsgroup rec.audio has very few FGAs due to the personalities
    involved and the nature of audio.  For that reason, this
    document is called a FAQ.

20.7 Why did I get a bitter reply when I posted a simple opinion?
    Some feel that rec.audio is populated by people with very strong
    opinions.  The whole audio industry is filled with opinionated
    people.

    However, for the most part, these people like voicing their
    opinions and reading others.  What may have sounded like a
    severe rebuttal may have instead been an outlet for the other
    person's frustrations or a challenge to you to "play the
    `rec.audio' game" and back up your words with some spirit.

    Be sure to stay light when reading rec.audio.  Otherwise, you
    are likely to take yourself and everyone else too seriously.
--
Bob Neidorff; Unitrode I. C. Corp.  |  Internet: [e-mail]
7 Continental Blvd.                 |  Voice   : (US) 603-424-2410
Merrimack, NH  03054-0399 USA       |  FAX     : (US) 603-424-3460
---