[sdiy] good for VCAs?

[eq927 at freenet.carleton.ca]

Fernando,
The Philips NE570 compander appnote describes what putting a VCA in the 
feedback loop of an op amp will do (plus other useful info).

I do not have a ready-to-go expo SSM2164 schematic; perhaps someone else 
on the list has tried it?

There is a problem with using very fast VCA's with very fast on/off 
envelopes - you get a quite noticeable click, except when the VCA turns 
on/off at the zero crossings of the audio signal. And this is after you 
have trimmed the VCA for minimum offset... often it is better if the VCA 
 takes a few hundred microseconds to a couple of milliseconds to reach 
maximum gain.

The OP275 looks like a very nice op amp to use if you want a dual op 
amp. BTW when I sent a message to your other address it bounced.
Regards, Mike