Let's talk about envelopes.

One helpful way of thinking about envelopes is:

Envelopes are used all over your DAW for many many things. They're one of the most important core components of pretty much everything you'll be doing with audio. Here we are going to learn all about them, and at the end you'll be able to read them and know what sound to expect.

How do they work?

Here's an example of an envelope that controls the volume of a sine wave.

Here we can see the volume (which is also the height, or in more mathy terms, the amplitude) of the sine wave is controlled by the envelope. This is what it would look like if we put them one on top of the other. This is actually what's going on with your amp envelope in all the synths, it's just controlling the amplitude of the wave, aka the volume.

It's worth playing with this a bit to really get a feel for it. I want to point out a couple things also:

• Attack Time is the amount of time (usually in milliseconds) from the beginning of the midi note, to the peak. For a volume envelope this peak corresponds to the volume you set your synth to. So if you're synth is at -6db, the peak will be -6db. So the attack time is the amount of time from -inf db to -6db
• Decay Time is the amount of time from the peak until we arrive at the sustain amount.
• Sustain Value is the only one of these controls that isn't an amount of time. It's an amount of the thing you're controlling with the envelope, so for a volume envelope the sustain value is the volume for the sustain portion of the envelope.
• This means that from the moment the midi note starts until the sustain portion starts takes [ attack time + decay time ]
• Release Time is the amount of time from when the midi note ends until the value goes back to 0. So for a volume envelope this would be the amount of time until the synth goes completely quiet after the midi note ends (aka -inf db volume).

Don't worry if that seems a bit confusing for now, as we go through and you play with the examples you'll start building your intuition for how they work, and eventually you won't even need to think about it you'll just know it in your bones.

Anyway, let's continue. Onwards!

What if the midi note ends before the attack and/or decay are finished??

As you can see, the release stage kicks in whenever the note ends, and if that happens to be during the attack or the release stage, the angle of the release changes. It seems sort of obvious when you look at it this way because it's not shown like this in your DAW, but I've seen many many wise people get tripped up by this.

Take a moment to mess around with the example to try out which kinds of situations might make the most unexpected envelopes.

Boom! That's all the basics of envelopes!

So now you know,
but before you go off into the world thinking you know all there is to know about envelopes, let's cover a couple more things. On the next pages we will cover:

• Why am I getting clicks at the beginning/end of my envelope? Aka: the mystery of the unexpected discontinuities
• Getting an intuitive, visual understanding of pitch envelopes
• Interactive visualizations of many envelopes controlling one signal
• Pimp my envelope: envelopes controlling envelopes controlling envelopes controlling...
• Why only ADSR? Why not ADSDFOIERFKMSDPCSDR or ADSDSKDFKKDDDKSDSRSR? Aka: Envelopes with as many points and curve types a person could dream of in an envelope utopia.
• And many more...

Onwards