Creating FM wavetables
FM synthesis is a synthesis method used in many synthesizers such as Yamaha DX series, Ableton Operator, Elektron Digitone, etc.
The FM tone is created by modulating the carrier oscillator with a modulation oscillator.
FM stands for frequency modulation, but it is actually phase modulation.
FM(t) = A * sin(2pi*Fc*t + B*sin(2pi*Fm*t) )
A = Carrier amplitude, Fc = Carrier frequency
B = Modulation index Fm = Modulator frequency
You can see that this formula is almost identical to the formula for how to change the phase of a waveform described in Tutorial vol.1.
From this equation we understand that FM is a phase modulation.
Creating FM wavetable
FM with a 1:1 frequency ratio
FM Synthesis 1-1
Examples of how to combine carriers and modulators
The timbre of the FM synthesis is determined by the way the carrier and modulator are combined. Here are some useful combinations.
The difference between FM Wavetable and FM Synth
The FM Wavetable requires that the frequency ratio of the modulator to the carrier be an integer. This is because the Wavetable has a fixed waveform length. So if you want to create a sound with a frequency ratio of 1 : 3.5, such as a bell, you will have to convert it to 2 : 7.
Next time: Modulation envelopes