Anatomy of a phaser

A phaser works by duplicating the input signal and applying a series (2, 4, 6 or 8 in Fazortan 2’s case) of evenly-spaced all-pass filters to one of them. The all-pass filters change the phase of the processed signal, as determined by their frequencies; and when mixed back in with the unprocessed signal, a series of cancellation notches and peaks emerge, creating that characteristic resonance. For emphasis of that resonance, the output can be fed back into the input.

The centre frequency is then modulated by an LFO – or, with Fazortan 2, the mixed output of two LFOs – sweeping the filters up and down cyclically. The waveform of the LFO is what defines the rhythmic style of the modulation – sharp but smooth with the triangle wave, obviously ‘stepped’ with the square wave, random and stepped with S+H, etc – and with Fazortan 2 blending two independent LFOs, there’s no limit to the shapes it can make.