Linear response VCA's

[Michael Maloney]

Thanks to everyone for their responses.

Just to address the questions or speculations that have arisen:

The envelope generator prototype running right now is based an an 8-bit
microcontroller running at 12 MHz (Z86E31) driving a 16 bit parallel DAC
(AD660). I got it running, watched it on a scope, and then got slammed with
work. So I don't have any hard numbers to throw around yet.

Ripple or zipper effect won't be a problem at this resolution. I can't see
speed being a problem either...but I'll see when I get a bit more time to
test.

However:

I "borrowed" the DAC from another system, and priced it later - oops!
$22.00 ea. It seems that a 16-bit parallel DAC capable of near-DC will cost
at least $15.00. I think that's overkill for the application. 

So I'm working on alternatives - will probably spend the next couple of
weeks playing with things: semi-discrete DACs, PWM techniques, switched
integrators, etc.


Mike Maloney