ADSR Envelope Explained: Attack, Decay, Sustain, Release

What does ADSR stand for?

ADSR stands for Attack, Decay, Sustain and Release, the four controls on the most common kind of envelope generator. An envelope generator outputs a control signal that rises and falls every time you play a note, and that signal can drive volume, filter cutoff, pitch or almost any other parameter.^[1]

The detail that trips most people up: three of the controls are times and one is a level. Attack, decay and release set how long each move takes. Sustain sets the height the envelope holds while the key stays down.^[2] Raising sustain never makes a note last longer. Holding the key does.

The four-stage layout is older than most DAWs. After discussions with composer Vladimir Ussachevsky in 1965, Robert Moog built an envelope module with controls labeled T1, T2, ESUS and T3, and ARP later simplified those names into the ADSR form every synth uses today.^[3]

What does each ADSR stage do to the sound?

Each stage controls one part of a note's life: attack is the start, decay is the first drop, sustain is the held body and release is the tail. Change one and the instrument character changes, even with the same oscillator and filter.

Attack: how the note starts

Between 0 and 5 ms the note hits instantly, which suits drums, plucks and most basses. Around 50 to 200 ms the note swells in the way bowed strings do. Past 500 ms you get pads that bloom slowly. For percussive sounds the attack should be as short as possible.^[2] On sine and triangle waves a true 0 ms attack can click, so 1 to 3 ms is a safer floor.

Decay: the first drop

Decay only does something when sustain sits below maximum. Ableton's Analog manual spells it out: with Sustain turned all the way down there is no sustain phase, and with it all the way up there is no decay phase.^[4] Short decays give a sharp accent; long decays make a note fade gently while you hold it.

Sustain: the held level

Sustain at 100% keeps a note at full level for as long as the key is down, like an organ. A sustain level of 0 produces a piano-like, percussive envelope with no steady level, even while the key is held.^[1] Most plucks and bells live at or near zero sustain.

Release: the tail after note-off

Release starts when the MIDI note ends. If you let go during the attack or decay stage, the sustain phase is usually skipped and the envelope moves straight into release.^[1] A release of 0 ms can click on sustained sounds. Multi-second releases smear chords together and keep voices busy.

Amp, filter and pitch envelopes: what is the difference?

The ADSR shape is the same everywhere; the destination is what changes. An amp envelope shapes loudness, a filter envelope shapes brightness and a pitch envelope bends the note, usually right at the start.

Ableton's Simpler, for example, has three classic ADSR envelopes for amplitude, filter frequency and pitch, with separate amount controls for the filter and pitch envelopes.^[4] In Serum, ENV 1 is wired to the amplifier and controls each voice's output volume, while the other envelopes only act once you assign them to a target.^[5]

• Amp envelope Loudness over time. Every patch has one, even when the synth hides it behind a single Release knob.
• Filter envelope Pushes cutoff up from the knob position and lets it fall back. Attack sets how fast the brightness arrives, decay how fast it fades, sustain where cutoff settles and the amount knob how far it travels. Filter behavior is covered in synth filter types explained.
• Pitch envelope Sweeps pitch, usually a fast drop from a few semitones above the note. Ableton notes the pitch envelope is especially helpful for percussive sounds.^[4] Kicks, zaps and 808 punch all start here.
• Mod envelope Any other target: wavetable position, FM amount, distortion drive, noise level.

Envelope amount can usually go negative. A negative filter envelope pulls the cutoff down at the start of the note and lets it rise as the envelope falls, which gives a reverse, swelling tone. FL Studio's sampler envelopes work this way: turning the Amount knob left of center inverts the envelope, and centering it switches the envelope off.^[6] For repeating movement instead of a one-time shape, use an LFO; see what an LFO is.

ADSR settings for plucks, pads, basses and leads

Start with the values below, then adjust by ear against the tempo of your track. These are starting points rather than rules: a pluck at 150 BPM needs a shorter decay than the same pluck at 80 BPM, because the next note arrives sooner.

For worked examples, trap bells and plucks apply the zero-sustain shape, and dark trap pads use the slow-attack, long-release shape with extra modulation on top.

How should you set the envelope on an 808?

An 808 wants a near-instant attack, a decay that ends before the next kick and a short release so the tail does not blur into the next note.

If you play a sample, the note length in the piano roll is the most precise envelope you have. Keep sustain at 100% and use a 50-150 ms release, so each 808 stops cleanly wherever the MIDI note ends. If you build the 808 from a sine, set the amp envelope to 0-2 ms attack, 0.6-2 s decay, 0 sustain and around 100 ms release, then add a pitch envelope for punch. The full build is in how to design 808s from scratch.

1. Zero the attack
   Set attack to 0-2 ms. Longer values soften the transient and the 808 loses its hit against the kick.
2. Set sustain and release
   For a sampled 808, sustain 100% and release 50-150 ms. For a synthesized one, sustain 0 and let decay decide the length.
3. Add a pitch envelope
   Route an envelope to pitch with an amount of about +12 to +24 semitones and a decay of 20-60 ms. The fast drop reads as a click and punch on small speakers.
4. Match length to tempo
   Trim decay or note length so the tail ends before the next kick. Faster songs need shorter 808s.
5. Check slides
   For gliding 808s, switch the synth to mono with legato so the envelope does not restart on every slide note.

How do envelopes work on samplers?

A sampler applies the same ADSR to recorded audio, so the envelope trims, softens or cuts a sample instead of shaping a raw oscillator. A long vocal chop with a short decay and zero sustain becomes a stab; the same chop with a slow attack becomes a pad.

FL Studio's Sampler channel adds three extras to the classic four stages: Delay before the attack, Hold at peak before decay, and Amount. Its envelopes stay off until you enable the LED in the envelope section, and a Tempo option makes the stage times follow the project tempo.^[6] Ableton's Simpler can loop its amplitude envelope in Loop, Trigger, Beat and Sync modes, and in One-Shot mode a Trigger option lets the sample keep playing after you release the key.^[4]

• Delay Waits before the attack starts. Handy for off-beat swells or for layering a second sound that enters late.
• Hold Keeps the envelope at peak for a set time before decay begins, so a sample's transient plays at full level before it drops.
• Curve or tension Bends each stage between linear and exponential. Exponential decays sound more natural on plucks and drums.
• Tempo sync Sets stage times in note values instead of milliseconds, so a gated chop stays in time when the tempo changes.

Vital uses the same six-stage idea: delay, attack, hold, decay, sustain and release, with slope controls on attack and release, according to a community-written Vital user guide.^[7] The Vital synthesizer tutorial shows where those controls sit.

Common ADSR mistakes and how to fix them

Most envelope problems come down to stage times that ignore the tempo or the next note.

• Click at the start Attack at a true 0 ms on a smooth wave. Raise it to 1-3 ms or enable oscillator phase reset.
• Click at the end Release at 0 ms on a sustained sound. Raise release to 10-30 ms.
• Muddy chords Release longer than the gap between chords. Shorten it until each chord ends before the next, or reduce the voice count.
• Fast notes sound weak Legato is on, so the envelope never restarts. Turn legato off, or turn it on only for slide passages.
• Every note sounds the same Map velocity to envelope depth or attack. Ableton's Analog, for instance, can shorten attack time at higher velocities.^[4]