[LAD] HDSP 9652 and Behringer ADA8000

[Fons Adriaensen]

On Thu, Mar 29, 2012 at 02:27:42PM +0200, Adrian Knoth wrote:

> Yes, ADA8000 is based on Alesis (now WaveFront Semiconductors) A/D
> (AL1101), D/A (AL1201), an ADAT encoder (OptoGen AL1401) and an ADAT
> receiver (OptoRec AL1402).
> 
> The ADA8000 is a copy of the RME AEB8-I (I had the scheme for it if you
> want), and the scheme is simply an expansion to 8 channels (instead of
> 2) of the appnote given by Alesis for OptoGen and OptoRec.

Which (the appnote) does not include the mic preamp. Strangely 
enough the ADA8000 preamp has a very good noise figure if used
at maximum gain (real max, not just close). It gets very bad
once gain is reduced. That is due to *bad design*, you can 
predict this (without even doing any calculation) by just
looking at the circuit diagram. And the line input is just an
attenuator feeding the mic preamp. I don't think all that is
a copy of anything RME. 

Apart from that, 50,150,250 Hz hum levels increase from left
to right (i.e. as you get closer to the power supply). Which
gets hot enough to fry some eggs if you take 5 mA of phantom
power from each input.

Ciao,

-- 
FA

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It's also a pipe-dream, founded on self-delusion, nerd hubris
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