On a synthesizer, unison stacks several voices at the same nominal pitch for each note. Small differences in tuning, position, and phase create a sound that is thicker, wider, and more complex than a single oscillator voice.
Main unison controls
Voices sets how many voices are stacked, Detune sets the pitch difference between them, and Spread or Width distributes them across the stereo field. Some instruments also control phase variation or stereo placement. Start with a small voice count and gentle detuning.
Sounds that benefit from unison
Unison is often used to enlarge leads, pads, and plucks. It can also be applied to bass, but excessive low-frequency width may weaken the center. Keeping the low end mono or applying width only to higher frequencies can preserve a stable foundation.
Pitch and phase considerations
Heavy detuning creates a stronger chorus effect but can make the pitch less precise. Wide voices may also cancel in mono and cause the sound to become thinner. Check the setting in both the complete mix and mono playback.
Voice count and processing load
Increasing unison voices makes each played note consume more polyphony. Long releases and dense chords can therefore increase CPU use and cause voice stealing. Use only as many voices as the sound requires.
Distinguishing the performance term
This article describes a synthesizer function. For multiple instruments or voices performing the same melody, see Unison as a performance and arrangement term.
