Good Queston #2: EG cap

[jhaible]

 Using
> OTA's for the "resistive" element, I generally find that I never need to
> go above .1uF to get agonizingly long time constants.  Just MHO.

Yes - and if you'd use larger values you'd get problems with *minimum*
time constants from typical 1mA OTA currents.
The larger values (uF range) of many non-VC envelopes is just because
it's hard to get potentiometers above 1 or 2 MegOhms.
Typical cap values of VcADSRs are in the 47nF or 100nF range.

JH.