In sound design, an ADSR envelope modulates the sound and sculpts its timbre thus changing its sonic character. ADSR is an acronym that stands for its four stages Attack, Decay, Sustain and Release. The contour of the ADSR envelope is specified by three time-parameters and one level-parameter like this:

(A) Attack time is the time it takes for the signal to go from minimum to maximum when the key is pressed.
(D) Decay time is the time for the signal to drop to the designated sustain level (if it is not set to maximum, then decay time has no meaning).
(S) Sustain level is the level of the signal while the key is hold.
® Release time is the time taken for the signal to fade out after the key is released.

Note that the signal will jump to the release stage when the key is released no matter where it is in the envelope. Hence if a short note is played, the signal might not had time to rise to the maximum in the envelope, therefore release will be relative to the level reached in the envelope.

Envelopes can be applied not only to volume, but also to filter frequencies or oscillator pitches.

To correctly tune the pitch envelope modulation range:

  1. First turn the modulation/envelope amount knob down.
  2. Press the key and set the desired minimum with the pitch knob (offset for modulation).
  3. Turn sustain level all the way up, press the key and let the signal reach maximum.
  4. While on sustain, dial the modulation knob to the maximum pitch.

About cutoff modulation, the cutoff knob is the starting point of the modulation, that means that the sound will not be altered if cutoff is set to maximum.

Moreover, it is sometimes possible to inverted the envelope and reverse its behavior.