Feature | The ultimate guide to digital synthesis
What is FM synthesis?
>Frequency modulation synthesis is notoriously complicated, and for those more used to working with analoguestyle subtractive instruments, it’s easy to be put off by jargon such as ‘operators’, ‘algorithms’, ‘carriers’ and ‘modulators’. When you break the concept down to its fundamentals, however, it’s not actually as impenetrable as you may think.
The basic principles behind FM are actually common in the analogue realm. Essentially, FM involves taking a simple waveshape – typically a sine wave – and altering its timbre by modulating it. If you’ve ever used an LFO to create vibrato by applying it to an oscillator’s pitch, then you’ve encountered a basic form of FM. The difference is that FM synths use audio-rate oscillators as opposed to the lower frequencies of an LFO. This audio-rate modulation is fairly common in the analogue realm too; synths like Arturia’s MiniBrutes, Moog DFAM or the IK UNO Synth Pro all let users create a simple form of FM by using one analogue oscillator to modulate the pitch of another.