10.6

Table Of Contents
284Logic Pro Instruments
Set the Logic Pro 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 first 32 harmonics. The tuning
relationship, or ratio, between the two significantly changes the base sound of 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 affect 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 EFM1 (see Logic Pro EFM1
global parameters).
Experiment with basic tuning ratios
In Logic Pro, do one of the following:
Set the modulator and carrier to the first harmonic—a 1:1 ratio.
A sawtooth-like sound is produced.
Set the modulator to the second harmonic and the carrier to the first harmonic—a 2:1
ratio.
A tone that sounds similar to a square wave is produced.
Choose a Logic Pro 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 significantly. These waveforms contain additional harmonics that add
a new level of richness to the resulting FMsounds.
Choose a different waveform
In Logic Pro, turn the Wave parameter knob.
If you turn the knob to the full-left position, the modulator produces a sine wave.
If you turn the knob clockwise, you step—or fade—through a series of complex
digital waveforms.