Sun Jan 9 11:15:41 EST 2011

Env mod: add or multiply

Mixing log and linear control voltages it becomes hard to keep track
of which signals need multiplication, and which need addition.

I.e. filter envelope depth: do we add pre-exp or post-exp?

Pre-exp seems best from numerical pov, but this doesn't seem to
correspond to how i.e. the Juno 60 works: envelope doesn't bring
filter to 0.