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Table Of Contents
Chapter 15 EFM1 177
Modulator and Carrier
The modulator and carrier parameters are outlined below.
Harmonic
In FM synthesis, the basic overtone structure is determined by the tuning relationship
of the modulator and volume envelope. This is often expressed as a tuning ratio. In the
EFM1, this ratio is achieved with the Modulator and Carrier Harmonic controls.
Additional tuning control is provided by the Fine (Tune) parameters.
You can tune the modulator and volume envelope to any of the first 32 harmonics. The
tuning relationship (or ratio) greatly changes the base sound of the EFM1, and is best
set by ear.
As a rule of thumb: even tuning ratios tend to sound more harmonic or musical, while
odd ratios produce more inharmonic overtones—which are great for bell and metallic
sounds.
As an example, the modulator and volume envelope set to the first harmonic (a 1:1
ratio) will produce a sawtooth-like sound. If the modulator is set to the second
harmonic, and the volume envelope to the first harmonic (a 2:1 ratio), the tone
produced will sound similar to a square wave. In this respect, the tuning ratio is
somewhat like the waveform selector of an analog synthesizer.
Fine
Fine tune adjusts the tuning between two adjacent harmonics (as determined by the
Harmonic control). The range of this control is ±0.5 harmonic. Dependent on the
amount of detuning, this will create either a subtle beating of the timbre or—if high
detuning amounts are used—adds new harmonic and inharmonic overtones.
In the center (0) position, Fine tune does not have an effect. You can easily center the
Fine tune control by clicking on the 0.
Modulator Wave
In classic FM synthesis, sine waves are used as modulator and carrier waveforms. To
extend its sonic capabilities, the EFM1 modulator provides a number of additional
digital waveforms.
When turned completely to the left, the modulator produces a sine wave. Turning the
Wave parameter clockwise will step/fade through a series of complex digital
waveforms. These digital waveforms add a new level of harmonic richness to the
resulting FM sounds.
Fixed Carrier Button
This button allows you to disconnect the carrier frequency from keyboard, pitch bend,
and LFO modulations.