Chapter V: Voice Programming; The Basics Of Fm Synthesis - Yamaha DX21 Owner's Manual

CHAPTER V: VOICE PROGRAMMING

1. The Basics Of FM
Synthesis
Before you begin actually programming or editing your own voices, a basic un-
derstanding of how digital FM synthesis works will be necessary. In the following
explanation we will discover how the DX21's FM voice generator produces complex
voices. This information will help you to understand the process and make it easier
for you to create and edit your own voices.
OPERATORS
The Yamaha DX series FM digital synthesizers use pure sine waves that interact
to create the full harmonic spectrum for any voice. Each digital sine wave oscillator
is combined with its own envelope generator to form an "operator".
Note that the operator's oscillator has two inputs: one for the oscillator pitch data,
and one for modulation data.
CARRIERS AND MODULATORS
The DX21 voice generator has 4 operators. When the output of one operator is fed
to the modulation input of a second operator—i.e. the first operator modulates the
second—a whole spectrum of harmonics is created that can form an incredibly
diverse range of complex waveforms (including the more conventional triangle,
sawtooth, and square waveforms). All this from just two operators!
2 3