FM synthesis
Use one wave to wobble another's pitch and metallic magic happens. The sound of the 80s.
FM synthesis makes new tones a completely different way — not by filtering a rich wave down, but by using one wave to wobble the pitch of another, thousands of times a second. Done fast enough, that wobble stops sounding like vibrato and starts adding whole new harmonics.
try it — FM
There are two oscillators: a carrier (the one you hear) and a modulator (which you do not — it just bends the carrier's frequency). Two knobs shape everything:
- The ratio is the modulator's pitch against the carrier. Whole-number ratios (2:1, 3:1) add harmonics that line up musically — bells, mallets, electric pianos. Fractional ratios (3.5:1) add harmonics that clash — clangs and metal.
- The index is how hard the modulator pushes — the brightness. Turn it up for busier harmonics; down for a near-pure sine.
Try 3.5:1 with a high index for a bell, or 1:1 with a low index for a mellow electric piano. Notice how the wave in the display gets more intricate as the index climbs — those are the new harmonics appearing.
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