The envelope generator (EG) generates an ADSR envelope. The envelope being the way in which the level changes with time and is controlled by the Attack, Decay, Sustain and Release parameters. Its function is to modulate a parameter over time, based on MIDI input or the amplitude of the input signal or side chain signal.
To add an envelope generator as a modulation source, click the + button in the source selection bar and click New Envelope Generator.
The following EG parameters are available (hold the mouse over a control point in the EG display to see which parameter it affects):
The EG can be triggered by three different kinds of input: MIDI note events, the main input signal, or the signal from the side-chain input. When MIDI is selected, the Threshold knob is hidden. Depending on the type and amplitude of the incoming signal you need to adjust the threshold for optimal functioning. Look at the top segment of the source button for the EG to see when it is in the triggered (Attack-Decay-Sustain) state. See also VST plug-in versions.
The time it takes for the attack to start after the key is pressed (or triggered when the side-chain signal exceeds the threshold).
The Attack portion of the envelope is the time taken for the amplitude to reach maximum value. Slow attack is commonly part of sounds called pads. But for percussive sounds the attack time should be as short as possible.
After the sound has reached its maximum level, it starts to decay until it reaches a level known as the Sustain level at a rate set by the Decay time setting.
This is the level reached after the decay time. The EG will hold this level as long as a key is pressed. Note that this parameter specifies a volume level rather than a time period.
Once the key is released, the value will remain at the sustain level for a time set by the hold parameter.
After the hold time the sound resumes its decay, this time at a new rate determined by the Release setting.
At the top right of the EG interface, the Presets button provides access to the EG section presets. The Remove button deletes the envelope generator. You can customize the default EG settings (used when creating a new EG) by overwriting the predefined Default section preset.
Next: Envelope follower
Drag-and-drop modulation slots