What Does an LFO Do on a Synth? Rate, Shape and Sync
12 hours ago
3 min read
What does an LFO do on a synth, and why does one small section have so many controls? An LFO adds movement without making you turn a knob throughout every note. We will connect rate, shape, sync and retrigger to the sounds you hear.
Table of contents
What does an LFO do on a synth?
An LFO, or low-frequency oscillator, repeatedly moves another synth parameter. You normally hear its effect rather than the LFO itself, which is why Roland describes it as automatic knob movement. The waveform defines the motion, Rate controls its speed, Destination chooses the parameter and Depth or Amount sets how far it moves. A destination with zero Depth produces no change. Sine and triangle move smoothly, saw rises or falls before resetting, square jumps between two levels, and Sample and Hold creates random steps.
How rate, tempo sync and retrigger differ
Rate sets the speed, either freely in Hertz or in beat divisions locked to tempo. One Hertz means one complete cycle per second, while tempo sync commonly offers quarter, eighth and sixteenth notes. Sync works well for rhythmic filter pulses, whereas free rates suit vibrato and slow drift.
Tempo can come from the synth, your DAW or MIDI clock, which is explained in our introduction to what MIDI is and what it is used for. Retrigger or Key Sync is a separate setting that restarts the waveform when you play a note. Without it, the LFO keeps running, so tempo sync alone does not guarantee that every note starts at the same phase or on the downbeat.
Also check
Which destinations make vibrato, tremolo and wobble?
Send an LFO to pitch for vibrato, amplitude for tremolo and filter cutoff for a sweep or wobble. Pan creates automatic left-right motion, while pulse width can animate an oscillator before it reaches the filter. The same triangle shape therefore produces a different result at every destination.
Vibrato: sine or triangle, moderate Rate and low Depth
Filter wobble: tempo sync, eighth or sixteenth notes
Tremolo: sine for smooth pulses or square for hard gating
Random drift: smooth random (or slow S&H for stepped drift) with very low Depth
How is an LFO different from an envelope?
An LFO normally repeats, while an envelope usually follows each played note through a fixed progression. Our explanation of ADSR and its four stages covers how attack, decay, sustain and release shape that progression. Modern synths can loop envelopes or run an LFO once, but the basic choice remains useful: use an LFO for repeating motion and an envelope for a note-shaped change.
How should you set an LFO?
Choose the destination first, raise Depth until the movement is obvious, set Rate and Shape, then decide whether you need sync and retrigger. Reduce Depth last, because subtle settings often work better once you understand the motion.
Add More Sounds to Ableton Wavetable
Ableton Structures Wavetable includes more than 40 premium sounds with custom macros and instrument racks. Use them alongside your own LFO experiments when you need a finished sound quickly.
More information
FOLLOW US ON
Comments