[sdiy] LM13700 questions

[David G Dixon]

> You *could* also do this with the two VCAs in series. The 
> first one would shape the audio with the envelope, and the 
> second one would alter the overall level according to 
> velocity - or vice versa. I think Paul Maddox's Monowave 
> works like this, IIRC.
> I suppose the advantage of your way is that you only have one 
> VCA in the audio path, so it should have lower noise/distortion.

Yes, that's exactly what I'd do as well.  The gain of amplifiers in series
multiplies, so this should do what you want.  As I said before, I do this
with 2164 all the time.  I have some circuits with three 2164s in series --
no problems (except that each amplifier adds a tiny bit of slew-rate delay
to the signal).  This would also be much easier to calculate, I should
think.