The FX Files: Uni-vibe

Producing the original ‘far out’ effect, the Uni-vibe emulated a rotating speaker with some success, although emulations have since eclipsed the bulky original...

The Uni-vibe was conceived as a pedal alternative to a Leslie speaker. It should come as no surprise, then, that one of its first proponents was Jimi Hendrix, who prolifically used a Leslie rotating speaker. Unlike most commercially-produced phaseshifters, the Uni-vibe doesn’t employ op-amps in its circuit, instead using discrete components in its design. At heart, it’s a four-stage phaser, with controls for intensity and output volume, as well as a mode switch for the colour of the pedal. Crucially, the speed control is tied to a foot pedal, and freed from the mechanical limitations of a motor altering its speed, the Uni-vibe can change speed much more dramatically. This meant that instead of the ‘fast’ and ‘slow’ options of a Leslie, the Uni-vibe’s speed was a continuous range.

Originally conceived by engineer Fumio Mieda for the legendary Shin-ei company, the unit was manufactured and distributed by Univox in North America from 1968 onwards. Although it was most common to see a foot pedal used to control the speed of the effect, a box with a potentiometer was an option. There were two main versions of the original unit. The first is distinguished with a grey power cord and hand-painted ‘Uni-vibe’ on the front; this is the true ‘Jimi’ version. The later version has a stencilled logo that is more silver in colour. Despite forum wars raging over which unit is the true classic, individual units differ greatly, leaving some collectors forever seeking out vintage specimens in pursuit of the ‘perfect’ Uni-vibe tone.

AT HEART, IT’S A FOUR-STAGE PHASER, WITH CONTROLS FOR INTENSITY AND OUTPUT VOLUME