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Chapter 4 EFM1 112
Set the EFM1 tuning ratio
The carrier frequency is determined by the played key, and the modulator frequency is typically a
multiple of the carrier frequency.
You can tune the modulator and carrier to any of the rst 32 harmonics. The tuning relationship,
or ratio, between the two signicantly changes the base sound of the EFM1, and is best set
by ear.
You use the Harmonic knobs to set the tuning ratio between the modulator (left) and carrier
(right) oscillators.
In general, even tuning ratios between the carrier and modulator tend to sound more harmonic
or musical, whereas odd ratios produce more inharmonic overtones—which are great for bell
and metallic sounds.
In this respect, you can view the tuning ratio as being somewhat like the waveform selector of
an analog synthesizer.
Note: The Harmonic and Fine tune knobs only aect the tuning relationship between the carrier
and modulator oscillators. These should not be confused with the global Tune and Fine Tune
parameters, which determine the overall tuning of the EFM1 (see EFM1 global parameters on
page 114 ).
Experiment with basic tuning ratios
Do one of the following:
m Set the modulator and carrier to the rst harmonic—a 1:1 ratio.
A sawtooth-like sound is produced.
m Set the modulator to the second harmonic and the carrier to the rst harmonic—a 2:1 ratio.
A tone that sounds similar to a square wave is produced.
Choose a dierent EFM1 modulator waveform
In classic FM synthesis, sine waves are used as modulator and carrier waveforms. The EFM1
modulator oscillator provides a number of additional digital waveforms, which extend its sonic
capabilities signicantly. These waveforms contain additional harmonics that add a new level of
richness to the resulting FM sounds.
Choose a dierent waveform
m Turn the Wave parameter knob.
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If you turn the knob to the full-left position, the modulator produces a sine wave.
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If you turn the knob clockwise, you step—or fade—through a series of complex
digital waveforms.