What is Uni-Vibe?
The Uni-VIbe was invented in the sixties as inteded to emulate the sound of a Leslie rotating speaker. The only problem was that it didn't really sound as a rotating speaker. But still, the unit sounded great in another way and the Uni-Vibe effect was born. It is built on phasing, but unlike regular phase pedals which uses aligned filters the Uni-Vibe is created through a staggered series of phasing filters. The result is a phase shifter that creates chorus and vibrato simulations.
Any good examples?
The most famous user of the Uni-Vibe effect is Jimi Hendrix who used it on songs like "Machine Gun" and his rendition of "The Star-Spangled Banner". Hendrix also used Leslie speakers from time to time, and sometimes it's a bit tricky to know where he used a Uni-Vibe and where he used a rotating speker. For some guidance, listen to the Uni-Vibe on the song "Hey Baby (Land Of The Rising Sun)" and to the Leslie on "Angel". Another notable user of this effect is David Gilmour of Pink Floyd, listen for example to his guitar sound on the song "Breathe". Also, Robin Trower is known to have used the Uni-Vibe on songs like "Bridge Of Sighs".
Which pedal should I get?
Dunlop has registered the trademark for Uni-Vibe but unfortunately their original pedal has been discontinued and can only be find on the second hand-market (the same goes for their Jimi Hendrix 70th Anniversary Tribute Series Univibe). But the people at MXR, a brand that is owned by Dunlop, has made a new version of this classic effect that is worth checking out. Roger Mayer, Hendrix's old pedal guru, has his own Uni-Vibe called the Voodoo Vibe. It sounds great, but might be a bit pricey. Other options includes the Fulltone Deja Vibe and the Voodoo Labs Micro Vibe. The old story "you´ll get what you´ll pay for" is most certainly true when it comes to Uni-Vibe, so it might be worth to save up some money for a great unit if you're interested in this effect.