Shaping sound onset to finish
Every synthesizer voice has a life cycle, and ADSR is the standard way to sculpt it. Attack (A) controls how quickly the volume ramps up after you press a key, measured in milliseconds. A 1ms attack on a lead synth feels snappy and punchy; a 200ms attack sounds swollen and slow. Decay (D) is the phase immediately after peak, where the volume drops to a sustainable level. This stage is often short, just a few hundred milliseconds, and gives the sound a natural breathiness.
Sustain (S) is the level that the envelope holds for as long as the key is held down. Unlike Attack and Decay, Sustain is specified as a level (0-100 percent) rather than a time, because it persists indefinitely. Release (R) is the final stage, triggered the moment you release the key, determining how quickly the sound fades to silence.
Designing envelopes for different instruments
Percussive instruments like kicks and snares demand fast attacks (1-5ms) and short decays, with minimal sustain. The envelope emphasizes the initial transient, the part of the sound our brain locks onto. String instruments simulate slower attacks (50-150ms) and longer sustains, mimicking the bow or pluck. Pads use very long attacks (500-2000ms) to create a swelling, ambient texture.
Release time is the secret ingredient separating amateur from polished synth work. A 5ms release on a bass synth sounds abrupt and cheap. A 100-500ms release creates legato smoothness and lets the sound decay naturally, especially when combined with reverb. Layering two instances of the same sound with different ADSR curves (one fast, one slow) is a classic technique for adding depth and movement.