Low-frequency Oscillator (LFO)

Low-frequency oscillator tremolo filter sweep Subtractive Synthesizer

The low-frequency oscillator (or LFO) rhythmically changes a synthesizer’s sound. An LFO has two main components: a rate and an amount. The rate determines how frequently the LFO completes a cycle. The amount determines the magnitude of that cycle.

Below are two LFOs that control volume and filter cutoff. Common musical terms for these effects are tremolo and filter sweep.

Play with the amount and rate sliders of each LFO to hear the effect they make.

It is called a low-frequency oscillator because the rate’s frequency is below the threshold of human hearing, around 20 Hz. Higher frequency rates would blur the effect and no longer sound rhythmic.
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