What Happens When You Modulate Envelope Attack, Decay and Release Times?

Modulating Envelope Stages with Control Voltage

Some envelope generators provide CV inputs for individual stages such as attack, decay, sustain and release.

These inputs open the door to a completely different kind of modulation.

A Special Characteristic

Envelope stages are time-based processes.

Once a stage is completed, the envelope immediately proceeds to the next one.

This has important consequences.

Modulating Attack Time

Suppose an LFO modulates attack time.

The attack phase may become shorter or longer.

However, if the attack becomes very short, it may end before the modulation source completes a full cycle.

The listener may therefore hear only part of the modulation effect.

Why Sustain Is Different

Sustain is a level parameter rather than a time parameter.

Its behaviour is therefore easier to perceive when modulated.

The modulation remains active as long as the sustain stage lasts.

Practical Considerations

Stage modulation is often most effective when applied subtly.

Extreme modulation can cause envelope behaviour to become difficult to predict.

Conclusion

Modulating envelope stages can create highly expressive control voltages, but time-based stages require special attention because their duration determines how much of the modulation becomes audible.

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