Rich Osman wrote:
> I'm working on a hobby project that processes several communcations 
> grade audio channels and I'm looking for a *cheap* way to get eight full 
> duplex audio paths. The on-board interface today is usually full deplx 
> stereo, so that's two.
> 
> I've been looking at cheap USB audio interfaces and they all seem to 
> have mic rather than line inputs, so a single channel input.  Does 
> anyone know of one that is line in and out, and full duplex?  I don't 
> really care about rate limits as long as I sample faster than 32K.  Most 
> seem ot do 44.1 and 48K natively.
> 
> Finally, Linux drivers are a nice to have, but not a requirement.

Cheap USB runs at 1.2k with 8 channels.  That's $100.  For $250 you
can get a PCI plug in card that does 8 channels in at 40kHz. (see
http://www.measurementcomputing.com/cbicatalog/cbiproduct_new.asp?dept_id=238&pf_id=1103&mscssid=2FRVECJPXPDQ8N03E959QUTLL20W4LC2)

To get full duplex you'll need to spend some more.  I guess the
questions you have to ask are why USB, and why 8 channels?  At 12 
bits/channel and 16 channels at 32k you need 6.2 Mb/s and cheap
USB is 12Mb/s, so it's possible.  But I doubt there's much of a
market for it, so it'll be hard to find.

If an 8 channel mixer costs less than $500, that might work better,
but I don't see how you'll get much under $500 for what you want.

Patience, persistence, truth,
Dr. mike

I'm working on a hobby project that processes several communcations 
grade audio channels and I'm looking for a *cheap* way to get eight full 
duplex audio paths. The on-board interface today is usually full deplx 
stereo, so that's two.

I've been looking at cheap USB audio interfaces and they all seem to 
have mic rather than line inputs, so a single channel input.  Does 
anyone know of one that is line in and out, and full duplex?  I don't 
really care about rate limits as long as I sample faster than 32K.  Most 
seem ot do 44.1 and 48K natively.

Finally, Linux drivers are a nice to have, but not a requirement.

Thanks,

Rich Osman