ADSR (Attack, Decay, Sustain, Release)

In-Depth Explanation

ADSR (Attack, Decay, Sustain, Release) is the four-stage envelope model that describes how a synthesizer's sound changes over time from note-on to note-off. Attack controls the initial rise. Decay controls the drop after the peak. Sustain sets the holding level. Release controls the fade after note-off. Together, these four stages define the shape and character of every synthesized sound.

How ADSR Works

An envelope is a voltage curve that controls a parameter over time. In most synthesizers, the ADSR envelope controls the amplifier (volume) and the filter (brightness). The four stages work as follows.

Attack

Attack is the time it takes for the sound to reach maximum level after a note is pressed. A fast attack (1 to 10 ms) makes the sound start instantly, like a drum hit. A slow attack (200 ms to 2 seconds) makes the sound fade in gradually, like a pad swelling. Attack shapes the transient of the sound.

Decay

Decay is the time it takes for the sound to drop from the attack peak to the sustain level. A short decay (50 to 200 ms) creates a plucky sound that hits hard then settles quickly. A long decay (500 ms to 2 seconds) creates a sound that gradually evolves from bright to dark. Decay is what separates a punchy synth bass from a sustained lead.

Sustain

Sustain is the steady level held while the note remains pressed. Unlike attack, decay, and release (which are time values), sustain is a level value (0 to 100%). A sustain of 100% means the sound stays at full volume while the note is held. A sustain of 0% means the sound decays to silence after the attack and decay stages. A piano has a sustain near 0% because the note decays even while held. An organ has a sustain of 100% because it holds steady until released.

Release

Release is the time it takes for the sound to fade from the sustain level to silence after the note is released. Measured in milliseconds or seconds. A short release (10 to 50 ms) cuts the sound off abruptly. A long release (500 ms to 3 seconds) lets the sound linger and fade naturally. Release creates the tail of the sound. A pad with a 2-second release continues to echo after the performer lifts their fingers.

Real-World Example

An independent producer wants to create three different synth sounds from the same oscillator. They use a free synthesizer plugin (Vital) and a MIDI keyboard controller.

Sound 1: Pluck bass. Attack: 2 ms. Decay: 150 ms. Sustain: 20%. Release: 40 ms. The sound hits instantly, drops quickly to a low sustain, and cuts off fast. This is the classic house music pluck bass. It punches through the mix and leaves room for the kick drum.

Sound 2: Lead synth. Attack: 5 ms. Decay: 300 ms. Sustain: 80%. Release: 200 ms. The sound starts quickly, drops slightly, then holds at a high level. When the note is released, it fades over 200 ms. This is a standard lead synth that sits forward in the mix and has a natural decay between notes.

Sound 3: Ambient pad. Attack: 800 ms. Decay: 1 second. Sustain: 70%. Release: 1.5 seconds. The sound fades in slowly over nearly a second, settles to a steady level, and fades out over 1.5 seconds after note-off. This creates a lush, evolving background texture.

The producer created three completely different sounds from the same oscillator by changing only the ADSR envelope. No other parameters were modified. Total time: 5 minutes. Total cost: $0.

Why It Matters for Independent Artists

ADSR is the single most important concept in synthesis. If you understand these four stages, you can recreate almost any synth sound you hear. You can also fix synth sounds that do not fit your mix.

Three practical tips:

1. Match the attack to the role. Lead sounds need fast attacks (1 to 10 ms) so they cut through the mix immediately. Pad sounds need slow attacks (200 ms to 2 seconds) so they sit behind the lead without competing. If your lead synth sounds weak, check the attack. A slow attack on a lead pushes it behind the drums, making it feel late and unfocused.

2. Use decay to control punch. Short decay times (50 to 200 ms) create punchy, percussive sounds. Long decay times (500 ms+) create evolving, atmospheric sounds. If your synth bass lacks punch, shorten the decay. If your pad sounds static, lengthen the decay and add filter envelope modulation so the brightness changes over time.

3. Set release to match the tempo. A release that is too long creates muddy overlap between notes. A release that is too short sounds robotic and choppy. At 120 BPM, a quarter note is 500 ms. Set your release to 100 to 250 ms for rhythmic parts, or 500 to 1000 ms for pads. Use tempo-synced release if your synthesizer supports it.

The ADSR envelope also applies to the audio filter. Most synthesizers have a second envelope for filter modulation. A filter envelope with fast decay creates a bright attack that darkens over time. Read our music production fundamentals guide for hands-on synthesis exercises.

Related Terms

• Synthesizer - The instrument that uses ADSR envelopes to shape sound
• Audio Filter - The processor often modulated by a second ADSR envelope
• MIDI (Musical Instrument Digital Interface) - The protocol that transmits note-on and note-off messages triggering the envelope
• Transient - The initial attack portion of a sound, controlled by the ADSR attack stage