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Table Of Contents
Chapter 20 ES2 205
Given the ES2’s ability to modulate Digiwaves, you can produce sounds reminiscent of
classic wavetable synthesizers from PPG and Waldorf (and Korgs Wavestation).
Linear Frequency Modulation
The principle of linear frequency modulation (FM) synthesis was developed in the late
sixties and early seventies by John Chowning. Its such a flexible and powerful method
of tone generation that synthesizers were developed, based solely on the idea of FM
synthesis. The most popular FM synthesizer ever built is Yamahas DX7. FM synthesis is
also found in other models of the Yamaha DX range and some Yamaha E-Pianos. In the
discipline of pure FM synthesis, the ES2 can’t be compared with these synthesizers, but
it can certainly achieve some of their signature sounds.
Between the Sine setting (when the sine symbol is selected) and the FM symbol of the
Oscillator 1 knob, a stepless control range—which determines the amount of
frequency modulation—is available. This parameter is also available as a modulation
address.
Note: Osc1Wave is optimized for subtle FM sounds, utilizing lower FM intensity
amounts. For more extreme FM modulations, the Router offers the Osc1WaveB target.
See the “Modulation Targets”, on page 222.
The frequency of Oscillator 1 can be modulated by the output signal of Oscillator 2.
Whenever it outputs a positive voltage, the frequency of Oscillator 1 will increase.
Whenever it is negative, its frequency will decrease.
The effect is similar to an LFO modulation, being used to create a vibrato (a periodic
modulation of the frequency) or a slow siren effect. In comparison to an LFO, Oscillator
2 does not oscillate slowly. In the audio domain, it oscillates a little faster than Oscillator
1 itself. Thus, Oscillator 1’s oscillation also accelerates and slows down within a single
phase, resulting in a distortion of the basic sine shape of Oscillator 1. This sine wave
distortion has the side benefit of a number of new harmonics becoming audible.
The effect of frequency modulation depends on both the modulation intensity and
frequency ratio of both oscillators. It also depends on the waveform used by the
modulating oscillator (Oscillator 2). The modulation that takes place varies according to
the waveform selection for Oscillator 2—it might even be an oscillation that is
synchronized to Oscillator 1! Given the 100 available Digiwaves, countless combinations
of modulation intensities and frequency ratios, the frequency modulation of the two
oscillators delivers an infinite pool of spectra and tone colors.