Dave Smith Instruments SYNTHESIZERS

I've been making some basic acid lines with the desktop evolver, and I've noticed that varying 
the envelope amount tends to sound a bit crappy, like the filter jumps in steps instead of 
opening smoothly, as it does with varying the filter cutoff.  I wonder if there is some kind of 
smoothing applied to the control voltage for the filter cutoff, but not for the envelope 
amount? it makes it pretty hard to do decent acid lines.