11.0

SUBTRACTOR SYNTHESIZER290
Envelopes - General
Envelope generators are used to control several important sound parameters in analog synthesizers, such as pitch,
volume, filter frequency etc. Envelopes govern how these parameters should respond over time - from the moment a
note is struck to the moment it is released.
Standard synthesizer envelope generators have four parameters; Attack, Decay, Sustain and Release (ADSR).
There are three envelope generators in the Subtractor, one for volume, one for the Filter 1 frequency, and one mod-
ulation envelope which has selectable modulation destinations.
The ADSR envelope parameters.
Attack
When you play a note on your keyboard, the envelope is triggered. This means it starts rising from zero to the maxi-
mum value. How long this should take, depends on the Attack setting. If the Attack is set to “0”, the maximum value
is reached instantly. If this value is raised, it will take time before the maximum value is reached.
For example, if the Attack value is raised and the envelope is controlling the filter frequency, the filter frequency will
gradually rise up to a point each time a key is pressed, like an “auto-wha” effect.
Decay
After the maximum value has been reached, the value starts to drop. How long this should take is governed by the
Decay parameter.
If you wanted to emulate the volume envelope of a note played on a piano for example, the Attack should be set to
“0” and the Decay parameter should be set to a medium value, so that the volume gradually decreases down to si-
lence, even if you keep holding the key down. Should you want the decay to drop to some other value than zero, you
use the Sustain parameter.
Sustain
The Sustain parameter determines the level the envelope should rest at, after the Decay. If you set Sustain to full
level, the Decay setting is of no importance since the volume of the sound is never lowered.
Attack
(time)
Decay
(time)
Sustain
(level)
Release
(time)
K
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Key Up
Level
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