Tag: synth basics

Most explanations of ADSR start with a diagram: a little mountain shape labeled attack, decay, sustain, release. It is accurate, and it teaches almost nothing on its own, because ADSR is not a shape you look at, it is a shape you hear. Four numbers control how a sound begins, settles, holds and disappears, and the only way to actually learn what each one does is to change it and listen to the difference.

This article does that. Each section below isolates one of the four parameters, explains what it controls, and lets you hear it directly in the synthesizer embedded further down, before putting all four together.

Attack: how fast the sound arrives

Attack is the time it takes a sound to go from silence to its peak volume once you press a key. At zero, the sound appears instantly, which is what gives a pluck or a hi-hat its percussive snap. Stretch the attack to a few hundred milliseconds and the same note fades in instead of hitting, which is the difference between a stab and a pad.

A useful reference point: most plucks and basslines sit near zero attack, because any delay before the note fully arrives reads as sluggish in a rhythm section. Pads and swells do the opposite, often with an attack of half a second or more, because the slow arrival is the entire point of the sound.

Decay: the drop after the peak

Decay is the time it takes the sound to fall from that initial peak down to whatever level you set as sustain. This is easy to confuse with attack, since both are time values, but they control different things: attack is the climb, decay is the fall that happens immediately after, whether or not you are still holding the key.

A short decay gives a sound a percussive character even with a slow attack, since the volume drops away quickly regardless of how it arrived. A long decay lets the peak linger before settling, which is common in plucky bass sounds that need an initial bite followed by a rounder body.

Sustain: the one parameter that is not time

Sustain breaks the pattern. Attack, decay and release are all durations, measured in milliseconds or seconds. Sustain is a level, not a time, and it only matters for as long as you keep the key held down. It answers one question: once the initial attack and decay have happened, how loud does the note stay while you continue to hold it?

Set sustain to zero and the sound always falls silent after the decay phase, no matter how long you hold the key, which is what makes plucks and short drum hits behave the way they do regardless of how long a note is technically held in your DAW. Set sustain high and the note holds close to full volume for as long as you keep it down, the way an organ or a held pad behaves.

Release: the tail after you let go

Release is the only stage that happens after you stop holding the key. It controls how long the sound takes to fade to silence once the note ends. A release of zero cuts the sound off the instant you release the key, which is what gives short, tight sounds their precision. A long release lets the sound ring out well past the point where you have already moved to the next note, which is where reverb-like tails and smeared, ambient textures come from, even without any reverb plugin involved.

Release is also the parameter most responsible for a mix turning to mud. A pad with a four-second release stacked under a fast arpeggio will bleed into every new note, blurring the rhythm underneath it. If a part sounds smeared for no obvious reason, release is usually the first place to check.

Putting the four together

Three reference shapes cover most of what you will build early on, and each one is really just a different balance of the same four parameters.

A pluck uses a fast attack, a fast decay, low or zero sustain, and a short release, so the whole note is essentially the attack and decay phases compressed into a fraction of a second. A pad flips almost every value: a slow attack, little to no audible decay, high sustain, and a long release, so the note blooms in gradually and lingers after you let go. A bass sits between the two, usually a fast attack for punch, a short to medium decay, moderate to high sustain so the note holds steady under a beat, and a short release so it does not bleed into the next note in the pattern.

None of these are rules. They are starting points that make the relationship between the four parameters audible, and once you can hear what each one is doing, adjusting them by ear becomes far faster than reading a manual.

Where this fits

ADSR is not unique to synthesizers. The same four controls, or a close variant of them, show up on samplers, drum machines and even some compressors, where attack and release control how the compressor reacts to a signal rather than how a note sounds. Once the concept is familiar from a synth, recognizing it elsewhere becomes automatic, which is one reason it is worth learning by ear early rather than treating it as one more preset menu to skip past.

If you want to see where the envelope sits inside the rest of a synth's signal path, alongside oscillators and filters, our article on how synthesizers work covers the full picture. And if ADSR is one of the first concepts you are tackling in a structured way, the five-phase path in how to learn electronic music production shows where it fits into the bigger sequence.