Josh Koffman wrote:

>>> They will be close together. One of them is basically an analog to
>>> digital convertor for live recording. I suppose I could just do a "Y"
>>> cable. What do you think? Any idea how long I could make one leg of
>>> the Y? I guess the only part that might be a bit scary is what might
>>> happen if the mixer supplies phantom power. I wonder how the audio
>>> interface would like that.

Since you were considering transformers, I think phantom power is out
anyway -- doesn't go through transformers. Anyway, you better make sure
that none of the mics requires phantom power. Any decent console should
allow to not use phantom power. (If some mics require phantom power, then
you need to design for that.)

> So I was thinking about this a bit more after David pushed me to
> consider a simple "Y" adapter, and I might have a problem.
> 
> The recording interface doesn't have mic preamps on every channel - it
> expects a line level signal. Ah well... 

Many mixer consoles have a "patch" jack or similar for every channel. That
would be the best way to split out a recording signal per channel. It's
usually preamplified but not otherwise processed.

If not, a differential op amp input stage coupled to two differential
output stages is all you need (per channel). Give it the needed
amplification to get to line level (maybe adjustable, maybe add a clip
indicator, maybe add one LED vu meter and a switch which channel it shows
or a push-button per channel), and you're done. Shouldn't be too expensive. 

Gerhard
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist