Introduction to Envelopes

A synth with no dynamics is like a cat that hasn't been tasered: They don't move as much and they're not as interesting as they have the potential to be.

Envelopes can help change all that.   They define how a sound works over time and are a vital component to developing quality synth patches.

So let's take a look at them...

What is an Envelope?

An envelope, simply put, controls a parameter of a sound over time.   This is generally used to control the volume of a sound or the filtering of a sound, but can be used in many other ways to great effect.

There are a few different types of envelope out there, but the most commonly used one where synths are concerned is the "ADSR" envelope.   Let's take a look at what that means...

What does it comprise?

The ADSR acronym stands for...

Attack

This is how long the sound takes to build up to full volume.   For example, when a violin is played, the note gets louder over time until it hits the full volume - increasing the attack can emulate this.

Decay

The decay time defines how long it takes to go from the full volume down to the sustain volume.   This can be very short, like a piano note that is loud to start and then quieter as the note continues, or quite long if the synth is less conventional.

Sustain

Sustain time is how long the note can be held down for before fading out.   This can sometimes be substituted for sustain level, which implies the note can be sustained forever and instead defines the volume at which the sound is sustained.

Release

This is the time taken for the sound to fade to zero volume after the note is released.   Again, a piano is a good example of this - when you press a key and let go immediately, there is a period of time where the note fades out, rather than stopping dead immediately after letting go of the note.


Some useful techniques

1. Filter Plucks

By routing an ADSR envelope with a very small decay time (around 400-600ms should do the trick!) to a low-pass filter's frequency, you can get that plucking sound that is heard in all kinds of music from trance to dubstep!

2. Sweeping Pads

Like strings, by increasing the attack, you'll really feel your pads swell up when they are held down for a while - if you make the filter envelope's attack even longer than that of the amp envelope, you'll have an even more dynamic sound that changes over time.

3. Punchier Percussion

Sometimes called shaping, by running your samples through envelopes you can change their dynamics - a snare can be made snappier, a Bass drum can have a quick high end click then filtered down to a low end rumble... thanks to envelopes, there's loads you can do to make your percussive samples different!