Doepfer

So, any suggestion on how to create a gate signal from an envelope for 
use by the sample and hold? So far, I can send gates from my A-190 and 
from my LFO. However, if I try using one of my envelopes as a gate 
signal, I get nothing. Do I need to drop the voltage or something so 
that it goes into the negative? 

I'm sure I'm missing something basic.