DR ROBERT: WHAT IS IT?
Dr. Robert is Aclam’s newest overdrive pedal. In a constant quest to reach the highest possible quality and functionality, we are delighted to bring you a perfect replica of the legendary Vox UL730 amp, famously used by The Beatles!
- Extra saturation function (Mach Schau!)
- Smart Track Fastening System
- High-end components and True Bypass switching
- The closest you can get to the rarest Vox amp
Introduced in 1966 these state-of-the-art guitar amps mixed a solid-state preamp with a tube power amp section.
Tubes were standard at that time but had the inconvenience of being voluminous and prone to fail, plus they needed bigger transformers due to impedance matching and power requirements. Transistors were the solution as they were way smaller, reliable and took much less energy to operate. So, in 1965, Vox engineer Dick Denney decided to develop a hybrid amp with a solid-state preamp and tube powered amp section.
Thanks to the relatively new transistor technology, lots of features could be added. Top of the line models included two channels with three band eq each, distortion, tremolo and reverb.
There were many variants with different power ratings, but the ones used by The Beatles were the UL730 (30w) and UL7120 (120w).
Unfortunately, aside from The Beatles, those amps weren't popularly used at the time and most of them ended being returned to Vox for their disposal.
Now they are the missing link between tube and solid-state amps.
The Dr. Robert is based on the Normal channel of our Vox® UL730 S/N: 3042. We traced the original tag board circuits and measured each component’s value to make the closest replica of the amp’s soul and character.
One of the keys of its tone is the “Middle” control which is one of the most interesting mid-range eq ever found on an amp. By turning it counterclockwise, a great amount of mid-frequencies will be subtracted creating a scooped sound. On the other hand, when it's turned clockwise it will bring out all the mids and the signal will build up in gain. By tailoring the “Middle” knob you can control both midrange and saturation.
As the solid-state preamp of the UL730 doesn’t create much distortion by itself we’ve coupled it with a custom FET saturation engine to mimic the attributes of the tube power amp section. Not happy with that, we’ve gone even further creating the “Mach Schau!” section, which adds saturation to your main sound and includes an independent volume control to allow you to have both a rhythmic and a solo tone.
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 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 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.
SMART TRACK FASTENING SYSTEM
All our pedals use a custom enclosure designed to match perfectly our Smart Track pedalboards. Using the side thumb screws, you’ll be able to lock safely the stompbox into one of our pedalboards. It also was designed with the other pedalboard options in the market in mind.
MACH SCHAU! FUNCTION
Extra saturation function via a footswitch with an independent volume control. Hit it when the venue’s manager wants you to play harder!
We’re so honored to have Mr. Klaus Voormann, designer of The Beatle’s Revolver album cover, sign the artwork for the Dr. Robert!
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. Carbon comp resistors, Nichicon Fine Gold and Wima caps, Alpha pots and switches makes the Dr. Robert a reliable pedal with a superb tone.
CIRCUIT TAILORED FOR BOTH GUITAR AND BASS INSTRUMENTS:
Although based on the UL730 preamp, the UL400 series (designed for bass) shared almost the same circuitry. When doing tests using different instruments and amps we noticed the Dr. Robert sounded flawless with bass too! By tuning the FET circuit a bit, we managed to make the Dr. Robert suitable for both guitar and bass. No low-end drops resulting in a prefect preamp and distortion tool to plug directly to the desk or into an amp.
SHE SAID SHE SAID
SGT. PEPPER'S (CASINO RHYTHM GT)
SGT. PEPPER'S (LEAD)
AND YOU BIRD CAN SING
Dimensions: 13,6 x 8,7 x 5,5cm (5,4” x 3,4” x 2,2”) with knobs
Bypass: True bypass
Current Draw: minimum 40mA
Power requeriments: 9V DC Center Negative 100mA minimum or a a 9V battery
Included: 1 x Anti-sliding rubber pad & 1 x Velcro® pad