Basic Synthesis: Part 3 – Envelopes

Envelopes are the key to the articulation of your sound. Without them your patch will immediately start off at full blast, and stay there, and then disappear all of a sudden when you let go of the key. Envelopes, although difficult to understand at first allow you to change that, so you can create expressive and dynamic sounds with your synthesizer.

The standard envelope is in 4 main stages, described below:

  • Attack – the sound rising up to its maximum level. If it’s set to nothing, the sound plays at full blast straight away, whereas if you set it quite high then the sound gradually fades (good for string sounds).
  • Decay – this is how long the sound stays at the level the attack brings it up to. If it’s set as high as it will go, it will stay at the maximum level forever (rendering the sustain stage useless).
  • Sustain – this is the level that the sound stays at after the decay stage has passed. Some synthesizers also have a dedicated ‘sustain time’ setting, which decays the sustain stage after an adjustable amount of time too.
  • Release – a bit like reverb at the end of your sound – it is how long the sustain level takes to die down to silence. Set the release to nothing and you won’t get that effect – it will be instant.

The key to programming envelopes on your synthesizer is to practice and visual the envelope. Think of it like a graph with 4 stages, and you are plotting points higher or lower on the domain as the sound changes through the stages of the envelope. The sound rises through the attack, it dies down through he decay, it stays at the selected level in the sustain, and when you let go it disappears through the release.

Filter envelopes are just that – they articulate the filter using an envelope. To do this, there is usually a knob dedicated to the filter frequency (cut-off point) just for the filter envelope. Turn the normal filter cut-off down, and turn the filter envelope cut-off higher, and then program the filter envelope like a normal envelope. Takes a while to figure out, but its worth it – for example, turn the sustain on the filter envelope off, forget about the release and attack (set them to zero), and make the decay short – then turn up the release and wow! The thing to remember here is that its not the volume (amplitude) that your changing, it’s the cut-off frequency with the envelope, so you can create great effects with clever programming – such as emulating brass sounds by increasing the attack on the filter envelope.

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