Feeding an FM operator back into itself converts it from a default low-passed wave to a true sawtooth

In FM8 and similar FM synthesizers, the default oscillator waveform is not a pure sawtooth — it sounds like a low-passed, softened version of a saw wave. To obtain a true, harmonically rich sawtooth, route the operator’s output back into its own input (self-feedback). In FM8 this is done by dragging the box above the oscillator upward; a circular arrow appears indicating feedback. As feedback amount increases, the wave progressively hardens into a richer sawtooth; at extreme amounts it tips into noise. A moderate feedback setting (around 30 in FM8’s scale) produces a convincing sawtooth. This technique matters in Reese/neuro-bass design because a genuine sawtooth provides the harmonic density that distortion and modulation will reshape into the characteristic sound.

Examples

In FM8: increase operator feedback from 0 to ~30. At 0: muted, soft wave. At ~30: full sawtooth character. At maximum: noise. The target is the sawtooth range — rich harmonics without aliasing collapse into noise.

Assessment

Explain why the default FM8 oscillator does not sound like a sawtooth; then describe the specific action in FM8 that introduces feedback, and the perceptual result at low, medium, and maximum amounts.