The Fulltone MDV 2 is Fulltone’s Custom Shop Univibe clone.
It’s all analogue — not just analogue, but no ICs or op-amps in the audio path. It uses 13 discrete transistors, four proprietary photocells, and a real incandescent light bulb. Old school!
These aren’t just affectionate nods to the past but they’re what the Univibe circuit needs to sound right. The photoresistors that most companies are incorrect. Fulltone had the original photocells reverse-engineered from scratch at significant expense because generally available components had the wrong resistance and response characteristics.
The original Univibe was a four-stage phaser effect built between 1968 and 1973, inspired by the Leslie cabinet and the vibrato of its physically rotating speaker. It used a tiny light bulb shining on four photoresistors housed under an aluminium shroud.
Funny thing — it didn’t really sound like a Leslie, but it certainly had a sound of its own. A thick combination of chorus and phasing that became one of the most distinctive sounds in rock music. e.g. Jimi Hendrix, David Gilmour, Robin Trower, and Frank Marino of Mahogany Rush.
Original Univibes are large, heavy, and inconsistent. They break, they’re hard to repair, and above all they’ve become collectable! , pushing used prices ever higher.
Fulltone’s Michael Fuller spent years collecting and repairing Univibes before concluding he could do better. The Deja’Vibe launched in 1993 — even then considerably cheaper than used originals. The CS-MDV mkII is the current state of the art: a genuine Univibe clone in a workable small box, with no shortcuts.
MDV mkII vs Earlier Deja Vibes — What’s Changed?
The core circuit is a four-stage phaser using a light bulb and photocells and is unchanged. That circuit is what the MDV is all about. But there have been meaningful improvements:
- Speed control now has an extended range and works linearly across the full sweep of the knob. This was a significant problem with the original — all the interesting stuff happened in a very small section of the control’s travel.
- Expression pedal jack added — compatible with virtually any expression pedal regardless of potentiometer value.
- 30% smaller enclosure than older MDV versions, while retaining top-mounted jacks.
- Twice the available volume of previous vibe clones.
- Super-low 10K ohm output impedance for easy pedalboard integration.
The result is, in Fulltone’s own words, the biggest-sounding vibe they’ve ever made or heard.
Controls
- Speed: Controls the rate of modulation from slow, warm warble to fast tremolo-like pulsing. The custom photoresistor design gives a linear response across the full sweep — no bunching up in one section of the knob’s travel.
- Volume: Controls the output level. The mkII has approximately twice the available volume of other vibe clones — enough to hold its own in a band mix when the effect is engaged.
- Chorus / Vibrato switch: Selects between Chorus mode (wet and dry blended — the classic Univibe phasing and warble) and Vibrato mode (wet signal only, for a more pronounced pitch-modulation effect). Classic Univibe recordings typically use Chorus mode.
- Expression pedal jack: Accepts a TRS expression pedal with any potentiometer value for real-time Speed control.
Internal Trimmers
Factory set and accessible by removing the bottom plate, but these do not need adjustment in normal use:
- Trimmer 1 — Intensity: Adjusts the current reaching the light bulb, controlling the depth of the pitch-bend vibrato and phasing.
- Trimmer 2 — Symmetry: Fine-tunes the rhythmic feel of the oscillator — the heartbeat-like pulse of a well-made Univibe clone. More open to personal experimentation than the others.
- Trimmer 3 — Exp Max: Sets the available speed range. Do not adjust without consulting Fulltone.
Key Features
- 100% analogue — no ICs or op-amps in the audio path
- 13 discrete transistors
- 4 x Fulltone proprietary glass-lens hermetically sealed photocells with correct resistance and response characteristics
- Real incandescent light bulb — as used in the original Univibe circuit
- Custom photoresistor Speed control — linear sweep, extended slow and fast range
- Chorus / Vibrato mode switch
- Expression pedal jack — compatible with any expression pedal regardless of potentiometer value
- Twice the available volume of previous vibe clones
- Super-low 10K ohm output impedance
- Top-mounted jacks — suitable for tight pedalboard spaces
- 30% smaller enclosure than older MDV versions
- Requires 18V DC, 35mA — ships with Fulltone IPS-18 18V power supply included
- Can also run from two 9V outlets in series using a Voodoo Lab PPY cable
- 3 internal trimmers for fine-tuning (factory set)
- 5-year limited warranty (original owner, non-transferable)
- Made in the USA
Power — An Important Note
The CS-MDV mkII requires 18V DC at 35mA and cannot run at 9V. The internal light bulb needs 18V to reach the correct brightness which determines the depth and character of the modulation. The Fulltone IPS-18 18V power supply is included in the box.
If you want to integrate the MDV mkII into a multi-outlet pedalboard supply, the CIOKS DC7 v2 is the ideal solution. Two 9V outlets in series using a Voodoo Lab PPY cable is an alternative.
Who Is The Fulltone MDV 2 For?
The MDV mkII suits anyone who wants the genuine Univibe sound and not just a generic phaser. The difference is audible. The warmth, pulse, and pitch character that a genuine photocell-based circuit produces is something that digital recreations and cheaper analogue approximations simply don’t capture.
Watch It In Action
FAQs
It is a four-stage phaser. Internally, the light bulb shines on four photoresistors. Modulation is created as each photoresistor changes with the light level. The bulb’s warm-up and cool-down characteristics is part of the Univibe’s sound
Chorus mode blends the wet modulated signal with the original dry signal. This is what gives the phasing and warble. Vibrato mode removes the dry signal entirely.
The light bulb requires 18V to work at the correct brightness, which in turn sets the depth and character of the modulation. At 9V the bulb is too dim and the effect is weaker.
Yes. The expression pedal jack is designed to work with virtually any expression pedal.
They allow tuning of Intensity (light bulb brightness and phase depth); Symmetry (rhythmic feel of the oscillator),;and Exp Max (speed range). It should eb said that all are factory-set by Fulltone and do not need adjustment.
In Fulltone’s words: no. Its the bulb and photocell interaction and the overall thermal response that gives the character. You can approximate, but not he real thing!
The circuit is essentially the same. The mkII Speed range and control is better, and it has more output, lower output impedance and an expression jack.
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