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Synthesis · glossary

Detune

Also called detuning, fine tune, oscillator detune

Detune sets one oscillator slightly out of tune with another, usually by a few cents (hundredths of a semitone). The two waves drift in and out of step, and the pair sounds thicker and warmer than one oscillator on its own.

A cent is one hundredth of a semitone, so 100 cents takes you from C to C#. Set two oscillators to the same note, nudge one a few cents sharp, and their waves slide in and out of step: they reinforce each other, then partly cancel, over and over. You hear that as a pulsing shimmer called beating.

The beating rate equals the difference between the two frequencies: an A4 at 440 Hz against a copy 10 cents sharp (about 442.5 Hz) pulses about 2.5 times a second. Each harmonic beats too, faster the higher it sits, so detune does the most for saw and square waves, the ones packed with harmonics.

DetuneWhat you hear
2 to 5 centsA slow drift, warm and subtle
7 to 12 centsThe fat shimmer of two analog oscillators
15 to 25 centsSour and wobbly, for lo-fi and effects

Most synths with two or more oscillators have a Detune or Fine knob for this. Two tips. Split it, with one oscillator 6 cents sharp and the other 6 cents flat, so the average pitch still agrees with a piano or guitar in the same song. And go easy on bass notes: the beating slows as the pitch drops, so at A1 (55 Hz), 10 cents gives one swell about every 3 seconds, which you hear as the bass getting louder and quieter out of time with the song.

Stack many detuned copies of each note and you get unison. Blend in a copy whose delay time an LFO keeps wobbling and you get chorus. How to make a synth sound bigger uses all three.

In Gelato Synth, Detune is on the Osc B page and moves the second oscillator up to 50 cents either way.

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