Uni-Vibe

The Uni-Vibe is a modulation effect that Shin-Ei built in Japan in 1967-68, designed to replicate the sound of a Leslie rotating speaker¹². It never quite got there. Instead it landed on a sound of its own: a slow, liquid sweep that players hear as a thick chorus with a wobble underneath, or as a deep vibrato when the dry signal is switched out. Jimi Hendrix made it famous on the Band of Gypsys record and at Woodstock, and Robin Trower built a career sound on it³⁴.

Under the name, the Uni-Vibe is not a chorus at all. It is a four-stage phaser, an optical one, using photocells and a pulsing light source where a modern phaser uses voltage-controlled resistors³⁵⁶. That circuit has been copied, reissued and reworked continuously for over fifty years, and it is still sold new today by Shin-ei itself and by a long list of other makers.

Where the Uni-Vibe came from

The story starts with the Leslie. Anasounds calls the Uni-Vibe "the first pedal designed to reproduce the sound of a Leslie cab"¹⁰, and Behringer's page for its own Uni-Vibe-based pedal says the original Shin-Ei unit from Japan was built "in the quest to replicate the sound of a Leslie rotating speaker" and ended up inventing a sound of its own instead¹. Tru-Fi's history of the effect dates the original to 1967-68⁷.

What it invented was a modulation character that Behringer describes as a signature warble and undulation surrounding an overdriven guitar tone, the sound behind Hendrix tracks like Foxy Lady, Purple Haze and Machine Gun¹. Voodoo Lab notes the effect reached that status through Hendrix's Band of Gypsys record and his Woodstock performance of "The Star Spangled Banner"³, and Dunlop says Hendrix used a vintage Shin-ei unit from 1969 to 1970¹². RockBoard's PedalPedia entry for the Dunlop UV1SC Uni-Vibe Stereo Chorus credits the same circuit with giving "Hendrix and Trower their hypnotizing rotating speaker sound"⁴.

How it works: a four-stage optical phaser

The circuit is basically a phaser. EarthQuaker Devices puts it plainly: "the effect's circuit is basically that of a 4-stage phaser"⁵. Voodoo Lab, describing its Micro Vibe, calls the original "a variation of a four-stage phase shifter" designed as a Leslie rotating speaker simulator³. Jed's Peds describes the same thing from the builder's side: "In its simplest form a univibe circuit is a staggered phase shifter known for its throbbing, hypnotic pulse and lo-fi sweep"¹³.

Two things separate it from an ordinary four-stage phaser:

• Staggered stages. Mr. Black notes the original Univibe uses a four-stage phase-shift network with a unique corner frequency per stage, rather than four identical stages¹⁴. That staggering is a large part of why a Uni-Vibe sweep sounds less even and more vocal than a standard phaser's.
• Optical control. Instead of voltage-controlled resistors, each stage's resistance comes from a photocell, a light-dependent resistor lit by a pulsing lamp or LED driven by the pedal's low-frequency oscillator. Electro-Harmonix, whose Good Vibes follows the same approach, says "Like the original Uni-Vibe, it uses photocells to create chorus and vibrato with a warm, undulating, liquid groove"⁶.

Tru-Fi's history adds a naming quirk: the makers heard "an incredibly unique and beautiful sounding phase sound that they actually labeled Chorus"⁷. So the pedal says Chorus on its switch, but the electronics are phase shifting.

The controls and the Chorus/Vibrato switch

A Uni-Vibe-style pedal is controlled by a small set of knobs and one important switch. Dunlop's MXR Uni-Vibe Chorus/Vibrato page explains the switch: "use the VIBE switch to select either Chorus Mode, dry signal mixed with pitch-shifted signal, or Vibrato Mode, only pitch-shifted signal"¹⁵. Chorus keeps your dry guitar sound and layers the modulated signal on top; Vibrato removes the dry signal so the pitch wobble is total.

The same switch appears across the family, described in each maker's own words:

For the knobs, the MXR Uni-Vibe uses LEVEL for effect volume, SPEED for sweep rate and DEPTH for modulation amount¹⁵. Wylde Audio's Rotovibe Chorus/Vibrato carries "the same intensity and speed controls"¹⁹. Speed is the control players most often want at their feet mid-song, and Dunlop sells a dedicated Uni-Vibe Foot Control that "allows for manipulation of the Uni-Vibe Chorus/Vibrato's Speed and effect/bypass functions"²⁰. Shin-ei sells its own Uni-Vibe Speed Control foot pedal, built for owners of an original vintage 1960s or 70s Uni-Vibe²¹.

Bypass that never fully bypasses

The original Uni-Vibe has a well-known quirk: switching it off did not take the circuit out of your signal path. Mr. Black puts it concisely: "the original simply killed the oscillator"¹⁴. The phase-shift stages stayed in line with the light source dark, so the pedal colored your tone even when the effect was off. That is part of the vintage character, and it is one of the first things modern versions change.

How current makers handle it varies:

• True bypass: Thermion's PowerVibe²², Electro-Harmonix's Good Vibes⁶, PedalPCB's VIIB Vibrato, which "completely removed from the signal path" the effect circuit when bypassed²³, and, per Tru-Fi's history, modern Univibe pedals generally²²⁶²³.
• Not true bypass, on purpose: Surfy Industries states its SurfyVibe retains a tone change as part of the vintage character²⁴.
• No bypass at all: Fairfield Circuitry's Modèle B has "no bypass switch, no light" and is always on²⁵.

The two original versions and the modern Shin-ei line

The original run produced more than one variant. The Uni-Vibe Companion site notes there were two main versions of the original unit²⁶. Tru-Fi dates the original Uni-Vibe itself to 1967-68⁷.

Shin-ei still builds the circuit today. The Vibe-2 uses "original vintage style Uni-Vibe circuitry featuring many NOS components" and a vintage-style Miyama Chorus-Vibrato switch¹⁸. The Vibe-Bro is described by the maker as the original Uni-Vibe circuit "recreated with modern design techniques"²⁷. Current Shin-ei list prices, as of October 2026:

Pedals based on the Uni-Vibe

Because Uni-Vibe is Dunlop's registered trademark¹¹, other makers borrow the circuit and rename it. Tru-Fi's history notes that "Modern Univibe pedals come in compact, pedalboard-friendly enclosures with true bypass switching and other modern features"². A sample of what is out there:

• Tru-Fi Ghost Vibe: "A True Uni-Vibe in a small footprint," true-bypass, with room for a 9V battery inside⁷
• Thermion PowerVibe: "captures the magic of the classic UniVibe in a compact pedal," true bypass²²
• Electro-Harmonix Good Vibes: Uni-Vibe-based, photocell chorus and vibrato, true bypass⁶
• Dunlop's own line: the MXR Uni-Vibe Chorus/Vibrato, which Dunlop says delivers "the same lush, chewy textures that players have used since the late '60s," updated for modern gigging¹⁵, plus the Wylde Audio Rotovibe¹⁹ and the Jimi Hendrix '69 Psych Series Uni-Vibe Chorus/Vibrato, a miniaturized take on the vintage Shin-ei unit Hendrix used from 1969 to 1970¹²
• DryBell Vibe Machine V-3, Dawner Prince Viberator, Retro-Sonic Chorus: each with its own Chorus/Vibrato switch¹⁶¹¹¹⁷

DIY builds

The Uni-Vibe is a popular DIY circuit, and the published build documents show why it is also a fussy one. Analogman's page quotes Dave Fox on the original's control configuration: "they use the same exact circuit. It's that annoying configuration where you need a dual pot and the wipers get tied together"²⁸. GuitarPCB's VIBE build document specifies a RATE B100K dual pot for exactly that reason, alongside VOL A100K, INT B25K and VOICE B10k controls, with a TL072 and TL074 doing the op-amp work and MPSA18 transistors in the circuit²⁹.

The optical side is where builders spend their time. The VIBE build document calls for four KE-1072 LDRs, each with a current-limiting resistor of 1k8 to 4k7²⁹, and includes a T1 1K trimmer for adjusting the circuit²⁹. Matching those four cells matters because each one sets the resistance of its own phase-shift stage.

GuitarPCB offers several Uni-Vibe-inspired projects:

• VIBE: "lush, syrupy Uni-Vibe-inspired tones, from subtle movement to deep swirl," with Intensity, Rate, Volume and Voice controls³⁰
• The Vibe: five controls, Intensity, Rate, Volume, Throb and Voice, and an ORDER 3PDT switch that places the Vibe before or after a fuzz; the build document says "The conventional Hendrix tone is achieved when the toggle is pointed at the Vibe, signifying that the Vibe comes first"³¹
• NostalgiTone Vibe Single: a PCB and matching plate promising "the lush, syrupy tones reminiscent of the original Uni-vibe circuits"³²

The Vibe's fuzz-ordering option is a nod to how the effect was actually used in the Hendrix era, with the vibe feeding an overdriven amp rather than sitting after a clean fuzz¹³¹.

Pedals on this page

Dunlop Uni-Vibe

MXR · Chorus

Dunlop UV1SC Uni-Vibe Stereo Chorus

Dunlop · Chorus

Electro-Harmonix Good Vibes

Electro-Harmonix · Vibrato

$165.1 list price

Dunlop MXR Uni-Vibe Chorus/Vibrato

Dunlop/MXR · Chorus

MXR Uni-Vibe

MXR · Chorus

$159.99 list price

Surfy Industries SurfyVibe

Surfy Industries · Vibrato

Shin-Ei Vibe-Bro

Shin Ei · Chorus

$1,295 list price

Red Witch Pax Harmonia

Red Witch Pedals · Chorus

Tru-Fi Ghost Vibe

Tru-Fi · Chorus

$299 list price

Thermion Powervibe

Thermion · Vibrato

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