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From: Joern Plewka J_Plewka@Amtrash.comlink.de
Subject: Re: AD516 quality - bullshit
Date: Mon, 21 Apr 97 20:35:00


tonid@elektron.pl (Tomasz Nidecki) -> "AD516 quality - bullshit"
(17.04.1997)

> 
> > Why do people say that AD516 Codec is much better than for example
> > Delfina's - how much difference is there really???
> 
> They do? They are lying. :) Sunrize has CS4215, ie. exactly the same codec
> 
> Toccata and Prelude have CS4231, too.. It seems Crystal is dominating the
> 
> By the way, I have always wondered the Sunrize pricing.. AD1012 was about

Toccata uses a CODEC from AD, which of cause is no high-end.
You can`t offer high-end with a CODEC. Even it`s slightly stupid to _try_
to get really high-end on the mainboard of a computer of more difficult
on a PIC. There are frequencies up to 100MHz (68060) but not sine, square
in Amiga. You can of cause try to do it best you can including things like
multilayer and a layout verified by f.e. crystal`s technicans.
Have a look at PC, they don`t care about anything and most boards are
offering very lame performance.
If you want high-end better take AEB or even the professsional version of
S/P-DIF and put the analog stuff into external boxes with separate
power-supply etc.

For Melody we used a DAC from Sanyo offering 96 dB S/N at least. Due costs
we were not able to use Multilayer or things like OP27,227. Of cause we have
a nearly closed groundplane and SMD only, but it`s not multilayer.
Good, cheap parts like TL072 (TI) and no styroflex but even 25-35Volts
Elkos (for cinch-level only) are used. We tried to avoid channel and supply
crosstalk...
One thing we did which is worse for bad audio-equipment (crystal f.e.
says it`s no good idea) is replacing the ~20Hz highpass with ~4Hz pass.
It`s nice if you`ve an Onkyo, Yamaha surround decoder, but cheap stuff
will force noice to the base.
Even it`s usefull to do a capacitive output because it`s easier to handle
in a difficult environment like a computer.

The problem is: Of cause you can use 22bit DAC, ADC from companies like
burr-brown and of cause _no_ CODAC, and for sure a separate device
for both stereo channels, separate power-supply, ground decoubling
(differential input). But these devices are _really_ expensive and
so is the design. Even you`ll need things like a box done with u-metall
to do the shielding vs magnetic noise. Of cause you`ll have to add a
programable input amplifier (with two DACs and OPs that cost $30 each
because these chips don`t offer monitoring and pre-amplifing like the
Crystal-CODAC...in final you have to select special devices to get no
phase-trouble like with toccata (removes suround f.e.).

BUT: Who would pay for that?!?! and why doing such conversation in a
     computer and not a seperate device...


> Now everyone knows about the wonderful quality of AD516 compared to Delfina

Useless discussion, IMHO. If it sounds nice without noice from CD-Readers
etc. (PC) it`s very fine for a computer....

    | /  /\  -----  --   Development Group : Joern Plewka
    |/  |  |   |   |  |
    |\  |--|   |   |  |    Melody   :  16bit MPEG-Sound-Board
    | \ |  |   |    __     Simmfonie:  Simm-Module im A3000(T)




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