The MXR Phase 90 has been a pedalboard staple since the mid-1970s. Since its introduction, this classic stompbox has remained relatively unchanged with just a single knob to control the speed of the phase shifting. When on a lower setting, the sound moves slower for broader sonic swells, while higher speeds offer more warbly motion. Whether you're chasing that Van Halen tone, trying to funk up your cleans or just experimenting, the single-knob Phase 90 is a proven place to enter the world of phase shifters.