Overview - Aclam Guitars Dr.Robert Vox UL730 User Manual & Safety Instructions

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Overview

The Vox UL700 amp series were the secret weapon
®
used by The Beatles to achieve the unique guitar tone on
Revolver and part of Sgt. Peppers. They were also used by
The Rolling Stones and Jimmy Page of Led Zeppelin.
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.
Only a small number of UL730 units survived (around
20/30 units as some renown Vox connoisseurs state),
attaining the title of being the most collectable Vox amps,
with prohibitively collector pricing.
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 "Mids" 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 "Mids" 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.
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