Tiptop Z3000 Smzrt VCO MKII - Manual (Page 13)

Frequency Modulation. -­ Basics
Frequency modulation (FM) synthesis is a technique
used to generate musically interesting sounds by
rapidly changing the basic frequency of a sound. The
pattern of change is created by another waveform with
a frequency within the range of human hearing.
In practice, it is as simple as connecting the audio
output of an oscillator to the frequency control input
of another oscillator. First, a number of considerations
need to be taken into account: waveform type, FM
input type, frequency ratio, and synchronization.
Frequency modulation starts with two or more
oscillators. The first (the modulator) is used to
modulate the frequency of a second oscillator (the
carrier). Typically, sine waves are used because they
are, ideally, free of harmonics, but modular systems
allow for the use of other waveforms. However, the
more complex the modulating waveform is the more
complex the resulting waveform. Too much complexity
and the waveform becomes noise and avoiding this is
one of the most significant aspects of FM theory.
There are many books that can explain the
fundamentals of FM synthesis in greater detail than
is possible here. Frequency modulation has been widely
used in digital synthesizers thanks to the stability and
precise tracking of software-based digital VCOs. The
Z3000mkII’s built-in arithmetic processor allows the user
to implement true FM in analog, and to build
harmonically rich sounds using a calculated synthesis
approach.
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