chung wrote:
Kalman Rubinson wrote:
On Fri, 06 Feb 2004 04:21:59 GMT, chung wrote:

Can you provide some examples of worthwhile mods?

Nothing recent since I have not done any or much DIY in the last 10
years. However, I can recall one example.

In the old AA DITB, all the chips, digital and analog, were fed with
+/-5V. The chip mfrs spec sheets for the output opamps showed a
substantial rise in THD with such a reduced PS voltage, especially
since the DITB output at 0dB is +/-2V. Changing the Vregs so that the
available voltages were +/-5V and +/-12V and fed to the appropriate
pins, I was able to realize and measure a significant reduction in THD
on the analog outputs. I also added larger output caps and heatsinks
on all the chips. (Of course, they would have gotten even warmer at
the higher PS voltage had they not been heatsinked.)

I think that AA's decision to use the same +/-5V supplies for
everything was based on (1) reduced parts inventory and (2) an earlier
choice for the analog opamps. Nonetheless, the results were an
improvement compared to a stock DITB.

Kal


What's an AA DITB?

Audio Alchemy DAC-in-a-Box, IIRC. One of the more talked-about
outboard DACs, some years ago.



--

-S.

"They've got God on their side. All we've got is science and reason."
-- Dawn Hulsey, Talent Director