Phaser

Basics of a Phaser Pedal

Phaser pedals also have also been a part of the electric guitar player's arsenal for quite some time. As one of the major three types of "pitch modulation" pedals, phasers also clone an original signal, modify that cloned signal and mix it back in with the original signal. Where chorus and flanger pedals employ a varying (modulating) delayed response that's added back to the original signal to create their characteristic sounds, phasers achieve their sonic blueprint through the use of all pass filters. These filters pass all of the signal at the same volume (amplitude), but apply different phase shifts (time delays) for different frequencies. This phase shifting is then modulated (varied) through the use of a low frequency oscillator (LFO). This technology sounds similar to flanging but it is noticeably different because the amount of phase shift (delay) varies depending on the frequency, where the flanger applies the delay (or phase shift) to every frequency the same. This is why the phaser has a swirling, less structured sound vs. the "airplane takeoff/landing" sound of the flanger.

Like flanging, phasers are typically controlled through sweep/depth/width, rate/speed, and resonance buttons. The sweep/depth/width button controls the width (range) of frequencies that are being modulated (varied). The greater the sweep/depth/width, the more dramatic the effect will sound. The rate/speed button defines how often the sweep/depth/width goes through it's "cycle". This is very easy to comprehend audibly when the speed/rate button is tweaked. As with the flanger, the resonance button increases the internal feedback. This internal feedback further enhances (volume wise) the time locations where the original signal and the "phase shifted" signals are reinforcing each other...i.e. "lining" up or "overlapping" on the sound wave graph.