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1991-09-08
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Box Plot For Windows 3.0
By Rick Carlson
Sparta Sound Co.
Copyright (c) 1990,1991, by Sparta Sound Co.
ALL RIGHTS RESERVED
!!!!!!!!!!!!!!! UNREGISTERED SHAREWARE VERSION 1.4 !!!!!!!!!!!!!!!!!
PLEASE REGISTER
****************************************************************************
*** Boxplot is distributed as Shareware. It is NOT a free Program. ***
*** If you use Boxplot then you should register it. ***
****************************************************************************
COPYRIGHT NOTICE
BOXPLOT is Copyright (c) 1990,1991 by Sparta Sound Co.
This document is Copyright (c) 1990,1991 by Sparta Sound Co.
Registered Boxplot users will recieve the latest version of
BOXPLOT which includes added features such as "system tuning" and
box dimensioning, as well as complete documentation and many more
speaker files from various popular manufacturers. Included in
the documentation is a tutorial on Loudspeaker enclosure design,
construction, and tuning. Registered users will also recieve mail
notification of major new releases of BOXPLOT.
If you are new to speaker building then I strongly recommend the
tutorial. Nothing is worse than spending many hours building a
speaker enclosure only to be disapointed because of lack of
proper construction and tuning.
==========================================================================
To register please send $25.00 to
Rick Carlson
62 Fox Trail Rd.
Sparta, NJ 07871
USA
Compuserve 71041,3015
See the README.DOC file for more information
*****************************************************************************
Introduction
Box Plot is a Microsoft Windows based program that calculates the
frequency response and maximum Sound pressure level for a sealed
or vented loudspeaker enclosure.
Boxplot is based on the Sealed or Vented box system. While there
are many other types of enclosures for loudspeaker systems
(Horns, Infinite baffle, Transmission lines), the Vented enclosure is
currently the most popular type among speaker manufacturers and audiophiles.
It is also one of the easier types to build correctly.
This Version of Box Plot requires Microsoft Windows 3.0 or later
to run. A math coprocessor is not required but greatly speeds
up the frequency response calculations.
This program can be used by audio hobbyist or professional to
design and modify high quality loudspeaker enclosures. You
should be familiar with the Thiele/Small loudspeaker parameters
in order to best utilize this program, but all that is required
is a basic understanding of vented loudspeakers and a good data
sheet for your drivers. I strongly recommend the tutorial for
beginners.
Operation:
This Program was designed to allow 'almost' real time update of
the response plot as box parameters are changed.This is usefull
when trying to shoehorn a speaker into a non optimum box. Many
different combinations of box parameters can be tried in a short
period of time. If Auto Plot is turned on, then clicking on the
OK button of the BOX Parameters dialog box will replot the
response curves. Autoplot can be turned off, for slower machines.
Speaker Parameters:
Speaker parameters are entered by bringing up the a dialog box
under Speaker, on the main menu. When you ar satisfied with your
changes, click on the OK button to save the parameters. The
parameter names are the Thiele/Small parameters specified on most
good spec sheets. Parameters can be entered in either metric or
english units. Selecting the meteric or english checkbox will
change the entire programs units not just the speaker parameters.
Fs Free air resonance of the speaker.
Vas Volume of air equivalent to the speakers compliance.
Qms Mechanical Q of the speaker.
Qes Electrical Q of the speaker.
Xmax Maximum linear cone displacement.
Pd Maximum power dissipation (in watts).
Re Dc resistance of the voice coil.
Diam Effective piston diameter of speaker.
Box Parameters:
Box Parameters are entered in a dialog box. When the OK
button is clicked the Box Parameters dialog box stays on the
screen. To close the dialog box click on the Close button or
use the system drop down menu (upper left of dialog box) to
close the box. The reason the dialog box stays on screen is
to make it easier to edit parameters and see the effect on
frequency response.
There are 6 types of boxes that can be modeled with Box Plot.
Closed Box:
Simple sealed Enclosure.
Closed Box with first order equalizer:
Sealed box with first order hi pass filter. The first order
filter usually provides subsonic attenuation.
Closed Box with second order filter:
Sealed box with a second order hi pass filter. The filter
is usually an active filter placed before the power amp.
Adjusting the Q of this filter modifies the low end response
of the system. This is usually used to extend the lower
3dB point.
Vented Box:
Box with a tuned port.
Vented Box with first order eq:
First order Eq is more usefull here than is a sealed box.
Because it will limit cone excursion at subsonic frequencies.
Vented Box with second order eq:
Same as sealed box.
Box Parameters:
Alpha: System Compliance ratio.
Alpha is the ratio of box volume (Vb) to speaker Vas.
Alpha = Vas / Vb
Alpha tells you how big to make the box.
H: System tuning ratio.
H is the ratio of the speaker free air resonance to
the system tuning frequency (Fsb).
H = Fs/Fsb
This determines how to design the vent.
Ql: Q from leakage losses.
This is the enclosure Q at Fb resuting from leakage loss.
(better boxes have higher Q's. This parameter must be measured
after the enclosure is built. Start with 7 as a good estimate.
Fe/Fs:
This is the ratio of the Equalizer resonant frequency to
the box frequency.
D
This is the equalizer Damping coiefficent. D = 1/Q
Comments:
The comments field is a text string, 255 chars long that
can be used to annotate the graph.
Vent Design:
This box will show the vent length based on the present
box/ speaker combination. The Air Speed mach number is the
vent air speed relative to the speed of sound. The air speed
should be kept below .2-.3 in order for wind noise from the
vent to be inaudiable.
Auto Plot:
When the Auto Plot menu item is checked, anytime a speaker
or box parameter is changed, the graph will be regenerated.
This keeps the graph up to date with the latest parameters.
This also may be annoying on slower machines so it can be
turned off.
File:
New:
This will reset all parameters to some predefined settings.
The settings are based on nothing at all, just some numbers
that wont do real wierd things. (The speaker parameters are
from a well known manufacturer.)
Save:
Save as:
This will save the speaker, box, and comments in the specified
file.
Open:
Read a file on the disk. The default file extension is .SPK
but has no real significance.
Print:
This will print the response curves as shown on the screen
along with the speaker and box parameters.
Printer Setup:
This will bring up the active printer setup box. Any changes
made in the setup box will be saved as the current printer
setup.
To register Please send $15.00 to
Rick Carlson
62 Fox Trail Rd
Sparta, NJ. 07871
Compuserve 71041,3015
I will send out a disk with the latest version of BOXPLOT,
the complete documentation, and the Speaker tutorial.
Registered users will recieve notification of program updates.
If you have suggestions, comments, bug reports or just feel
like writing please do so.
Let me know what other kinds of programs would be usefull to
the audiophile.