What is LFO (Low-Frequency Oscillator)?
An LFO (low-frequency oscillator) is an oscillator running below audible frequency that is used not as a sound but as a modulation source — automatically moving parameters like filter cutoff, pitch, volume or pan in a repeating cycle.
In techno, LFOs are the main engine of hypnotic movement: a slow LFO on a filter makes an eight-bar loop evolve continuously; a tempo-synced LFO on volume creates rhythmic gating; a subtle LFO on pitch adds analogue-style drift. Key parameters are rate (speed, free or tempo-synced), shape (sine, triangle, saw, square, random) and depth (how far the target parameter moves). Layering several slow, unsynced LFOs is a classic trick to keep long loops from sounding static.