Aclam Guitars Dr Robert Overdrive pedal is an accurate replica of the iconic VOX UL730 amp tones. Made famous by The Beatles as they used it on Revolver & Sgt. Pepper’s albums. The Beatles were not technicians or gear experts, but were so talented in making the gear made available to create the iconic sounds that worked for their songs!

Only 100 units of this Vox hybrid amp were produced and most of them were destroyed. Probably only 25 exist today and due to the collectibility cost a huge money. The Vox UL730 has a solid state preamp and a tube power section making the sounds it made quite unique. The Dr Robert pedal is an overdrive or “amp-in-a-box” that does not sound like other overdrives. Even the art work was done by Klaus Voormann who designed the Revolver album cover.

As a Beatle fan that has chased this tone for years, I had to buy this pedal as soon as I heard the demos. This pedal is not just for Beatle fans as the Stones and other bands in the 1960s also used these rare Vox amps.

The VOX UL400 series (designed for bass) almost have the same circuitry than the VOX UL730 preamp.The Aclam Guitars Dr Robert Overdrive pedal can be used for Bass guitar as well.

The guitar overdrive pedal that replicates the legendary Vox UL730 amp
The Dr. Robert is a guitar overdrive pedal based on the Normal channel of our Vox® UL730 S/N: 3042. This amp in a box pedal was designed to be the closest replica of the amp’s soul and character. A meticulous process of tracing the original tag board circuits and measuring each component’s value has resulted in a sonic approach never reached before.

One of the keys of this amp in a box pedal tone is the “Middle” control which is one of the most interesting mid-range eq ever found on an amp. From subtracting mid-frequencies creating a scooped sound, to adding them to build up the sound in gain; tailoring the “Middle” knob will allow you to control both the midrange and saturation of this amp in a box pedal. As the solid-state preamp of the UL730 doesn’t create much distortion by itself, it has been coupled with a custom FET saturation engine to mimic the attributes of the tube power amp section.

This amp in a box pedal will also allow you to add saturation to your main sound using the “Mach Schau!” section of the guitar overdrive pedal, with an independent volume control to swap between rhythmic and solo tones.

The most accurate replica of the original UL730 preamp
Sometimes you can’t trust the internet or an old schematic! We’ve found major discrepancies between the published schematic and the real thing, such as component types and values, so we can assure this guitar overdrive pedal is the closest you can get to the rarest Vox amp! Following the preamp there’s a custom FET based circuit emulating the saturation produced by the UL730 EL84’s tube power amp section. Additionally, the circuit for this guitar overdrive pedal works with the same voltages found on the original amp thanks to a charge pump circuit which takes the 9VDC from the battery or DC plug and converts it to 18VDC.

Mach Schau! Function
Extra saturation function for this amp in a box pedal via a footswitch with an independent volume control. Hit it when the venue’s manager wants you to play harder!

“Mach Schau!” was shouted by the businessman from one the Hamburg’s venues when The Beatles resided in Hamburg when energy fell flat, and they had to put on more of a show.

Custom graphics by Revolver’s cover artist, Klaus Voormann
We’re so honored to get Mr. Klaus Voormann, designer of The Beatle’s Revolver album cover, to sign the artwork for the Dr. Robert amp in a box pedal!

High end components and True Bypass switching
We made an extra effort to put the finest and closest components to the original amp on the Dr. Robert guitar overdrive pedal. Carbon comp resistors, Nichicon Fine Gold and Wima caps, Alpha pots and switches makes the Dr. Robert a reliable amp in a box pedal with a superb tone.

Dr. Robert tech specs:

  • Dimensions:13,6 x 8,7 x 5,5cm (5,4” x 3,4” x 2,2”) with knobs
  • Bypass: True bypass
  • Power requirements: 9V DC Center Negative 100mAminimum or a 9V battery
  • Current draw: ≈40 mA
  • Included: 1 x Anti-sliding rubber pad & 1 x Velcro® pad