fm()

Category

Oscillator / Waveshaper

Description

Frequency modulation oscillator: carrier phase, modulation ratio, and modulation index. Index values around 0.1 to 6.0 move from subtle vibrato to bright FM.

Arguments

• x: phase or signal input; for pitched oscillators use X for the played MIDI note
• ratio: frequency/sync/modulation ratio
• index: parameter or oscillator index

Typical Values

Use moderate values first, then increase modulation depth while listening for clipping, aliasing, or excessive filter resonance.

Example

fm(X, 2.0, 1.5+4.0*param(2))

Notes

For pitched oscillator functions, X already contains the current MIDI note pitch and transpose information. Prefer saw(X), sin(X), or pwm(X, 0.4) unless you intentionally want an octave or ratio shift such as 0.5*X or 2*X.