Frequency modulation (FM) synthesis is often viewed as complex, but it’s a powerful tool for creating twisted bass sounds. Think of regular vibrato, where an LFO – the modulator – modulates the pitch of an oscillator – the carrier. Now imagine that LFO’s rate speeding upto the audible frequency range. This fast modulation introduces additional frequency content to the original tone.
By applying modulation over time via envelopes and LFOs, we can introduce complex harmonic movement into a static synth tone. These modulations can be pushed into saturation and distortion stages – either within the synth itself or external plugins – to create gnarly, rasping basses. Check the tutorial audio demo here and read the step by step tutorial by Music Radar.
Source: Music Radar