FM¶

The 4 operator frequency modulation (FM) sound engine is a powerful tool for crafting rich and complex sounds. Instead of fixed ‘FM algorithms’ the modulation matrix can be used to setup modulation between the 4 operators.

Operators¶

An operator is a single sine wave oscillator with an envelope. An operator can be configured to modulate the phase (and thus frequency) or another operator which can turn a simple sine wave into a sound with a complex spectrum. By varying the amount of modulation and setting different pitch ratios between the modulator and the carrier (the operator that is being modulated) a variety of sounds can be created. Each operator has the following controls:

x volume sets the loudness of the operator. If the operator is used as modulator this parameter sets how much modulation is applied to the carrier(s) who it modulates. Higher amounts of modulation create brighter and more complex sounds.
x ratio sets the frequency ratio relative to the note that is played. Setting this to values rounded to .0 or .5 will result in more harmonic sounds while other values will sound more inharmonic and create tension and beatings.

Operators used as modulator have an attack → decay → end envelope while operators used as carrier have an attack → hold → decay envelope.

Modulation matrix¶

The modulation matrix is used to set which operators modulates which. An operator can modulate multiple other operators, but only operators whose number is higher (and visually on the right side). The modulation matrix mappings are included in Morphing and can be changed using the numpad buttons:

../_images/synthesis-fm-mapping.png — The numpad buttons can be used to enable/disable modulation.¶

Numpad mapping:¶
`shift`	`1→2`	`-`	`-`	`files`
`edit`	`1→3`	`2→3`	`-`	`samples`
`no`	`1→4`	`2→4`	`3→4`	`FX`
`yes`	`-`	`-`	`-`	`settings`
`pattern`	`note_list`	`cue`	`morph`	`clock`

Feedback¶

Operator 2 has a feedback parameter which means the output of the operator is used to modulate its own phase. Operator feedback can be used to add harmonics:

2 fb sets the amount of feedback. Increasing this parameter will turn the operator from sine wave into a sawtooth then into harsh noise.
2 fb color changes the timbre of the operator when feedback is applied.