Appendix A: The Digitone Fm Synthesis; Overview; The Operators - Elektron Digitone User Manual

APPENDIX A: THE DIGITONE FM SYNTHESIS

A.1 OVERVIEW
At its core, the Digitone is a four operator Frequency Modulation (FM) synth in the style of the classic 80s
implementations. However, unlike the early FM synths, the Digitone use its FM engine more like a complex
tone generator than a complete synthesizer voice (although it does have this capability too). The Digitone
signal path is more similar to a typical subtractive synth than a classic FM voice.
The idea of this design is to harness the raw, and often complex, soundscapes of FM synthesis and use a
more well-known and approachable subtractive method for the overall sound shaping.
FM is a synthesis method where you add harmonics to the timbre by using modulation or layering to shape
the sound. You add harmonics by modulating one oscillator's pitch with the output of another oscillator. FM
works similarly to how you would apply vibrato via an LFO. At slower modulation rates, it is simply vibrato,
but when the modulating frequency reaches audio rate, the vibrato effects becomes a part of the sound and
becomes a timbral effect instead.
A.2 THE OPERATORS
In FM synthesis the oscillators are called operators. Unlike the analog oscillator, the operator also contains
an envelope and specific input and outputs, making it a sort of macro oscillator. FM combines two or more
operators to generate a more harmonically rich output. An operator that is used to modulate another opera-
tor is called a modulator. The operator that generates, or carries, the resulting tone is called a carrier.
Feedback is used to increase the sharpness of a sound. Feedback is only applied to modulators. The output
of the operator is fed back into itself, resulting in added harmonics. In Digitone, an operator with feedback
with a parameter value around 35 results in a sawtooth waveform. If pushed to higher values, the feedback
soon results in noise. For more information, please see "11.3.7 FDBK" on page 40.
FM Overdrive
Base-width
Filter
Operator
Waveform
Modulation
input
Feedback
Carrier
Wavelength
(frequency)
(ratio: 1)
Modulator
(ratio: 8)
Output
APPENDIX A: THE DIGITONE FM SYNTHESIS
Amp
Multimode
Filter
Envelope
Output
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