LFOs and oscillator modulation
What’s also great is that you’re not just restricted to using a dedicated LFO
A synth’s low-frequency oscillator is essentially a ‘regular’ inaudible oscillator that operates at low speeds, and is used to modulate other parameters – kind of like an extra hand wiggling a knob for you at the rate and shape you set. LFOs in the semi-modular world are especially useful, as signals can be piped wherever you choose thanks to those patchbays. Plug an LFO’s CV output straight into an oscillator’s frequency/pitch input, and the LFO will wobble the pitch: instant vibrato. Plumb an LFO output into amplitude input and you’ll modulate volume for tremolo goodness. Plus, making those physical connections yourself will help you plan out your modulation strategy and get to grips with what’s going on from the start.
Attenuators are massively helpful when patching LFO signals: by plugging the LFO’s output into an attenuator’s input, then the attenuator’s output into the destination of choice, you can use the attenuator’s knob to temper the amount of LFO modulation, effectively giving you a ‘mod amount’ knob. And you can also mix modulation signals together for unique mod shapes.
What’s also great about the semi-modular and modular worlds is that you’re not just restricted to using a dedicated LFO; you can take any oscillator signal’s output and use it to modulate any other signal with a CV input. Some oscillators can be tuned so low they become LFOs in themselves, but the real fun starts when you modulate other parameters with oscillators for audio-rate sideband effects. Using an audio-rate oscillator to wobble the pitch of another audible oscillator is rudimentary FM synthesis, but unlike the idiosyncratic FM-synth world of operators and carriers, your purposeful patching will again guide your process – and you can modulate pretty much anything using an audio-rate source.