Sequential PRO 3, User Manual

Page: 43 / 168

31 Pro 3 User’s Guide Filters
Filter Envelope
The Pro 3 filter has a dedicated, 5-stage envelope generator (attack,
decay, sustain, release, plus delay). The Filter Envelope is used to shape
the harmonic characteristics of a synthesized sound by giving you filter-
ing control with these stages.
This is one of the most important aspects of a synthesized sound. Without
an envelope, the filters would be static and unchanging. They would stay
open or closed by a fixed amount that wouldn’t change over the duration
of a sound. That’s not very expressive or interesting to listen to — and
it’s not how most real-world instruments behave.
In general, sounds produced by an acoustic instrument are brighter at
their beginning (the attack stage) and grow mellower as they die out (the
decay and release stages). In other words, their harmonic content changes
over time. This is exactly what the filter envelope is designed to emulate.
VELOCITY ATTACK DECAY SUSTAIN RELEASE AMOUNT
ATTACK DECAY SUSTAIN RELEASE AUX ENV AMOUNT
VELOCITY ATTACK DECAY SUSTAIN RELEASE AMOUNT
1 2
ENVELOPES
AMP
FILTER
AUX
Filter Envelope
attack decay sustain release
amplitude
time
note off note on
delay
A typical 5-stage DADSR envelope