9

Frequency Modulation (FM) Synthesis
Put simply, FM synthesis involves the use of a modulator oscillator and a sine wave carrier
oscillator. The modulator oscillator modulates the frequency of the carrier oscillator within
the audio range, thus producing new harmonics. These harmonics are known as sidebands.
FM
Modulator oscillator
Carrier oscillator
Resulting waveform
Typically, FM synthesizers don’t incorporate a filter. You can generate some subtractive
synthesizer style sounds with FM synthesis, but it is difficult to recreate the sound of a
resonant subtractive synthesizer filter with this method. FM synthesis is extremely good,
however, at creating sounds that are difficult to achieve with subtractive
synthesizers-sounds such as bell timbres, metallic tones, and the tine tones of electric
pianos. Another strength of FM synthesis is punchy bass and synthetic brass sounds.
Logic Express includes a simple FM synthesizer, the EFM1. Although it is minimalist, it is
capable of producing many of the classic FM sounds made famous by Yamaha’s DX series
of synthesizers (the DX7, sold from 1983 to 1986, remains the most commercially successful
professional-level hardware synthesizer ever made).
The ES2 also features some FM techniques that allow you to modulate one oscillator with
another. You can use these FM techniques to partially bridge the gap between the very
digital sound of FM synthesis and the fat analog sound that the ES2 is noted for.
Component Modeling Synthesis
Also known as physical modeling, this synthesis method uses mathematical models to
simulate instruments. Parameters are used to describe an instrument’s physical
characteristics, such as the materials the instrument is made of, the dimensions of the
instrument, and the environment it is played in—under water, in air. Equally important
are descriptions of how the player would interact with the instrument—for example,
whether it is played by plucking, bowing, or strumming strings; by hitting it with sticks;
by placing fingers on sound holes; and so on.
368 Appendix Synthesizer Basics