flangers

A flanger is an audio modulation effect that creates a swept, comb-filtered sound by mixing an input signal with a copy that is delayed by a small amount and whose delay time is continuously varied. The resulting phase cancellations produce notches and peaks in the frequency spectrum that move up and down, giving a characteristic swoosh or jet-plane effect.

The term originates from early tape delay techniques, where engineers would route a signal onto two tape machines and gradually vary the relative speed of the tapes. The slight, time-varying delay produced by the differing machine speeds creates the moving comb filter sound. Modern flangers use either analog delay lines, such as bucket-brigade devices, or digital processing, but they reproduce the same basic effect: a modulated delay fed back into the input to strengthen the effect.

Typical controls include depth (how much the delay varies), rate or speed (how fast the LFO modulates the delay), and feedback (how much of the output is fed back into the input to increase resonance). A mix or dry/wet control determines the balance between the original signal and the flanged signal. Some units offer additional parameters such as resonance, manual delay offset, or tempo-synced modulation.

Applications and usage vary across genres, but flanging is commonly used on electric guitars, vocals, and keyboards to create space, movement, and a futuristic or psychedelic texture. While highly desirable in moderation, heavy feedback or long delay times can cause excessive self-oscillation or muddiness, so careful adjustment is typical.