tags: mus-407 delay delay-line

Flanger

The flanger effect is a [variable delay effect] that derives from a phenomenon called repetition pitch in which a [noise] source gains a sense of [pitch] when combined with a delayed copy of itself.

• introduces a "spectral sweep" that colors the sound

First documentation by Christian Huygens, 1693; noise from water fountain reflected from evenly-spaced stone steps.

Early notable use in Mammy's Boogie, Les Paul (1945)

• two tape recorders with identical input
• pressure applied to flange (edge of tape reel) to vary speed slightly
• [mixer] combines two inputs

Digital Implementation

Flanging can be implemented as follows:

• delay time modulated by low-[frequency] [sine wave] (0.1-20 Hz)
• delayed signal has subtle fluctuations in pitch
• combined input + output has sweeping peaks and nulls in [spectrum], resulting from [constructive/destructive interference]
• peaks occur at integer multiples of $1/D$ Hz, where $D$ is the delay time in seconds
• nulls occur linearly between peaks, at odd [harmonic]s of $1/(2D)$ Hz

Flanger effects have similar sound to [phaser] effects

• could be considered a "sweeping" [comb-filter] effect
• flanging → variable-delay [comb-filter]
• phasing → variable-delay [all-pass-filter]