Oscillator sync locks harmonic partials to a fixed relative phase, but on non-harmonic partials it injects extra harmonics

Enabling oscillator sync (hard sync to a master) on the additive partials forces them to restart phase together, ensuring all harmonic partials keep a fixed relative phase — useful for a consistent, coherent waveform. Applied to non-harmonic (inharmonic) partials, however, the forced restart introduces extra harmonics that are hard to control (though these can be a desirable metallic/clangorous colour). Combining sync with FM changes behaviour too: with sync engaged, FM no longer shifts pitch but instead creates additional harmonics. On the Nord Modular the slave FM sinewave oscillator provides sync, at slightly higher DSP cost than the plain slave sine.

Examples

Nord Modular FM slave sinewave oscillator: sync input available. Harmonic partials synced -> consistent, coherent tone. One inharmonic partial synced -> hard-to-control extra harmonics, potentially useful for metallic textures. Morph a piano into a clangorous sound and the sync switch’s effect grows because more partials become inharmonic.

Assessment

Describe what happens to an additive patch’s sound when you enable oscillator sync on (a) all harmonic partials, (b) one inharmonic partial — and why each scenario produces a different outcome.