From www.proguitarshop.com, the Retro-Sonic Phaser is based on the classic MXR Phase 90 Script logo. This is the same vintage 4 stage phase circuit with a few new additions to make it a more versatile pedal. Instead of just handling the speed of the effect, the Retrosonic version includes Rate, a Depth control which allows you to dial in the intensity of the effect, and a level control for matching unity gain or adding some signal boost. Retro-Sonic matches a set of FETs for the best possible phasing experience and uses the highest quality components. And of course, True Bypass is standard as well as a heavy duty enclosure