The Yamaha AN1x Synthesizer mailing list

Is the decay on the pitch envelope the same shape as the decay on the 
filter envelope?

For what it's worth I did a semi-objective test and here are the 
results. The envelopes aren't different as far as I can tell with the 
tools I have. However pitch sweeping the  the resonant filter with 
the filter envelope (subjectively) provides a very different sound 
than pitch sweeping a sine wave (Edge=0) through the same pitch in 
the same amount of time. This is due partly due to the signal 
strength at various frequencies. The filter resonance is strong at 
high filters and fades out at the low frequencies, the oscillator is 
pretty consistent throughout. For an imitation of a percussive Bwap, 
I found the oscillator version more interesting.

So how did I test the envelopes? Well I set up a pitch sweep (sine 
wave traversing from 11,835 hertz to 335 hertz in roughly 14 seconds. 
For the filter sweep, I obtained a resonant sine wave and then 
traversed it from a pitch of 11,811 hertz to 335 hertz in roughly 14 
seconds. (Hertz readings were obtained from a frequency analyzer.)

I put the two sweeps side by side in a visual frequency analyzer, and 
try as I might I could not prove that the pitch envelope was any 
steeper within the precision of the frequency analyzer's graph. Both 
sweeps looked relatively exponential.

So my instincts were wrong as far as the instrument can tell. Still, 
I learned two things:
- the filter is way louder at higher frequencies. 
- the pitch envelope sweep is much more satisfying for short blips 
and bwaps. Why? I don't know. So for plucked string sounds I'll be 
using the pitch envelope to control sync or fm modulations.

Hope this is of interest to someone.

Jerry