TLDR:

"An LFO is a sub-audio territory signal that modulates other parameters - from gentle vibrato to wild filter sweeps and rhythmic movement, there are many different shapes and speeds to use."

What is an LFO?

LFO stands for Low-Frequency Oscillator. It’s just like a regular oscillator, but slower (lower pitched) - usually below the range of human hearing. Instead of generating audible sound, LFOs are used to modulate other things, like pitch, filter cutoff, amplitude, or anything else you want to animate.

Think of LFOs as hands turning knobs for you, over and over, on a smooth loop (or not-so-smooth, depending on the waveform).

Common LFO Waveforms

• Sine: Smooth up and down motion.
• Triangle: Like sine, but more linear. Still chill.
• Square: Instant jumps between values - great for abrupt on/off or rhythmic gating.
• Saw / Ramp: Rising or falling slopes - good for repeating envelopes or punchy modulation.
• Random / S&H: Chaotic, stepped voltages - makes your patches feel alive.

Uses in a Patch

• Vibrato / Tremolo: Modulate pitch or volume slowly for subtle movement.
• Filter Sweeps: Move cutoff frequency automatically.
• PWM (Pulse Width Modulation): Animate square waves for classic synth tones.
• Wobble, Pulse, Bounce: Just generally make stuff wiggle.

LFOs are everywhere - they're the backbone of modulation. Whether you’re doing subtle shifts or wild generative chaos, LFOs make your patches feel less static and more alive.

Great Video