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Chapter 4 EFM1 110
EFM1 modulator and carrier parameters
Modulator and carrier overview
In FM synthesis, the basic sound is generated by setting dierent tuning ratios between the
modulator and carrier oscillators and by altering the FM intensity. The tuning ratio determines
the basic overtone structure, and FM intensity controls the level of these overtones.
At the core of the EFM1 synthesis system is a multiwave modulator oscillator and a sine wave
carrier oscillator. The basic sine wave of the carrier oscillator is a pure, characterless tone.
To make things more sonically interesting, you use the modulator oscillator to modulate the
frequency of the carrier oscillator. This modulation occurs in the audio range—you can hear it—
and results in a number of new harmonics becoming audible.
The pure sine wave of the carrier oscillator is combined with the newly generated harmonics,
making the sound more interesting.
Changes to the ratio of the two oscillators is achieved by adjusting the Harmonic parameters,
found in both the Modulator and Carrier sections. Additional tuning control is provided by the
Fine (tune) parameters.
FM Intensity knob
Carrier parametersModulator parameters