The most accurate replica of the original UL730 preamp

We’ve found some internet and old schematics but major discrepancies between the published schematic and the real thing were detected. We checked every component type and value so we are 100% sure this is the closest you can get to the rarest Vox amp.

The pedal also works with the same voltage the original amp does, the circuit takes the 9VDC and converts it to 18VDC.

Mach Schau! (extra feature)

Get more saturation with an independent volume control. Use it in solo parts to raise the volume or just to have more distortion with the same volume.
"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.

High end components and true bypass switching

You will find the finest and closest components to the original amp on the Dr. Robert: Carbon comp resistors, Nichicon Fine Gold and Wima caps, Alpha pots and switches...

Dr. Robert works for guitar & bass players

The VOX UL400 series (designed for bass) almost have the same circuitry than the VOX UL730 preamp.
We tunned the FET circuit so Dr. Robert sounds flawless with bass too. No low-end drops resulting in a great preamp and distortion tool to plug directly to the desk or into an amp.

Bass and Treble internal controls

The original VOX UL730 had a 3 band eq: Middle, Bass and Treble.
Middle control is the one that helps to tailor the tone better, that is why this is one of the main controls. You can access to Bass and Treble controls inside the pedal. Check out the internal controls section to know more about this.

Artwork made by Klaus Voormann

Klaus Voorman, designer of The Beatle’s Revolver album cover sign the artwork for the Dr. Robert.

The "Middle" control is one of the keys of this amp in a box, 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 the Dr. Robert. 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.

The original UL730 had a 3 band eq, but since the Middle control is the one that helps to tailor the tone better we decided to put the Bass and Treble controls inside the pedal. Just to make the user interface cleaner and easier to operate.

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.