lesson
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A raw synthesizer oscillator produces a relentless, static buzz that never changes. What transforms that raw electronic wave into a snappy plucked bass or a lush, swelling orchestral string section?
The secret lies in shaping the sound over time using an envelope generator. In the mid-1960s, electronic music pioneer Vladimir Ussachevsky suggested a standardized four-stage control model to Robert Moog, creating the classic ADSR envelope.
📊Interactive diagram
Why are three of these stages measured in milliseconds, while one is measured as a percentage?
Time vs. Level Stages
Attack, Decay, and Release are time-based parameters measured in milliseconds (ms) or seconds (s). They determine how quickly the envelope travels between different voltage levels.
Sustain is an amplitude level (from 0% to 100% or 0 to 1.0), not a duration. It sets the steady-state value where the signal rests as long as you hold down a key.
📊Interactive diagram
Now that we understand the four stages, where do we send this control voltage inside our synth patch?
Amp vs. Filter Envelopes
The Amp Envelope (VCA EG) controls the Voltage Controlled Amplifier, determining how loud the patch is from the moment you hit the key until after you let go.
The Filter Envelope (VCF EG) modulates the cutoff frequency of the filter over time. An envelope amount knob sets how high the filter opens during the attack and decay phases.
📊Interactive diagram