What is an LFO and how do you use it?
An LFO modulates parameters over time to add movement to your sounds. Here is what it does and how to apply it.
LFO stands for Low Frequency Oscillator. It generates a repeating wave shape that is used not to produce sound directly, but to automatically move a parameter over time.
Think of it as a hand turning a knob back and forth at a steady rate. Point that hand at the filter cutoff and you get a pulsing wah effect. Point it at volume and you get tremolo.
LFO wave shapes and what they do
- Sine: smooth, even modulation. Good for tremolo and vibrato.
- Triangle: similar to sine but with sharper peaks. Slightly more aggressive.
- Square: snaps between two values. Creates gating or stuttering effects.
- Sawtooth: ramps up then cuts. Creates a rhythmic sweep effect.
- Random (S&H): jumps to a new random value at each step. Good for glitchy or unpredictable textures.
Key LFO parameters
Every LFO has a rate (how fast it cycles) and a depth (how much it moves the target).
- Rate: set in Hz for free-running or synced to BPM (1/4, 1/8, etc.)
- Depth (amount): how far the parameter moves. Zero depth = no modulation.
- Phase: where in the cycle the LFO starts
- Target: the parameter being modulated (pitch, filter, volume, pan)
Practical LFO uses
- Filter cutoff: creates the classic synth wobble in dubstep and bass music
- Pitch: adds vibrato to leads and pads
- Volume: creates tremolo (rhythmic volume pulsing)
- Pan: moves a sound left and right for stereo width
- Wavetable position: morphs the timbre over time in modern synths like Serum or Vital
Frequently asked questions
What is the most common use for an LFO?
Modulating the filter cutoff is the most common LFO application. It creates the classic wobble effect heard in dubstep and bass music. Pitch modulation for vibrato is the second most common use.
What is the difference between an LFO and an envelope?
An LFO repeats continuously at a set rate. An envelope triggers once per note and follows a set shape from attack to release. Both modulate parameters, but envelopes are one-shot and LFOs are cyclic.
What does syncing an LFO to tempo mean?
Syncing locks the LFO rate to the project BPM. A rate of 1/4 means the LFO completes one cycle per quarter note. This keeps the modulation rhythmically locked to your track.
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