A couple of decades ago several small amp
manufacturers, noting the demand for used
Fender amps, started to produce amplifiers using old Fender circuits, capitalizing
on the simplicity of operation and purity
of tone of these classics. I invested in a
Clark Piedmont (’ 59 Bassman) and a Clark
Beaufort (narrow panel Deluxe) and so am
well acquainted with the high standards
used to produce these replicas.
It didn’t take Fender long to figure out that
there was a market waiting for reissues of
some of their most revered models, and thus
followed a steady stream of amps that bore
the Fender logo and looked just like the
amps of yore. Most contemporary players
understood the choice of the first series of
reissue models, but sometime around 2004
the ’ 57 Twin (model 5E8-A, also known as
the low-power Twin) came out, and the less
vintage-oriented players scratched their gearheads and wondered.
What’s up with the ’ 57 Twin?
The first Fender amps (and most others) were
born out of circuits printed in the back pages
of tube manufacturers’ catalogs suggesting ways to use their new audio tubes. The
early circuits based on these primitive tubes
were simple, and the initial amp models were
wimpy, but somewhere against the hum of
these primordial beasts the sharp report of
the starter’s pistol signaled the beginning of
the amplifier race.
The subsequent Twin Amp models featured
four output tubes and high-power or solid-state rectifiers and many more output watts,
making them suitable only for very loud rock
gigs and large venues.
Leo Fender could not play the guitar, but he
had a knack for translating into products the
suggestions and demands of those who could.
Most of his advisers were the country guitar
and steel players of southern California, with a
few big-city rock ‘n’ rollers thrown in. The professional players wanted loud. They needed to
fill the sonic space of large ballrooms, dance
halls, roadhouses and outdoor celebrations
without the benefit of the Front of House
monoliths that are seen at today’s large venues. Beginning in 1952 at 25 watts, the Twin
Amp was Leo’s answer to this demand.
Meet the Beastie
The ’ 57 Twin RI is a replica of its predecessor
manufactured by the Fender Custom Shop
(with a few changes thrown in for versatility’s
sake). The nicely applied lacquered Tweed cloth
covers a finger-jointed, solid-pine cabinet with
a thin leather handle (more on that later). The
chromed steel vertical chassis houses high-quality components mounted on a sturdy black
fiberglass eyelet board, sturdy tube sockets,
and nicely done point-to-point wiring. The
switches, jacks and pots are high quality and
the transformers and choke are from the highly
regarded Mercury Magnetics Company. There
is a bias adjustment pot on the circuit board.
Comparing schematics of old and new,
there are some relatively important differences. The original used three 12AY7 preamp tubes (but the same AX as the phase
inverter). There is no bias adjustment pot
on the original, and output tube plate voltages have been increased in the reissue
to 450V from original 400V. There are also
a couple of internal fuses on the new circuit (good idea). The new circuit is geared
toward a brighter, louder sound, with the
flexibility of being able to adjust bias on
output tubes to provide a more customized
sound and allow changes of output tubes
from one brand to another.
The Twin underwent constant modification and
several model changes in the years to follow.
As the models changed, the power output
increased. What is unique about the 5E8-A
is that it used two 5U4 rectifier tubes (higher
power rectifiers had not been invented yet) to
prevent the sag of the attack/decay envelope
and allow a decrease in the negative feedback
loop to the tone stack. This made the Twin
loud and punchy enough to cut through, but
also allowed another browner, spongy tone
favored mainly by Blues players by simply
removing one of the rectifiers.
The tube complement includes four Sovtek
12AX7WCs, relabeled Groove Tubes 12AX7-
R; two Groove Tubes-6L6GE (made in the
USA) and two Electro Harmonix 5U4GB rectifiers. The speakers are 12” Eminence Alnicos
designed by Ted Weber (of Weber VST),
which look remarkably like Weber P-12Ns.
The top rear-positioned control panel features five chicken-head knobs, which all traverse from 1–12 (take that, Nigel). There are
separate Bright and Normal channels, each
with its own preamp circuit, separate Volume
controls and two jacks, followed by Treble,
Bass, and Presence controls that are common
to both channels.
A few design considerations are in order for
us “filament brains” and non-tech types as
well. The old Fender amps were not very
consistent in sound, due to the fact that the
factory tended to use whatever components
they had on hand at the time, often of loose
tolerance, which led to variations in circuit
voltages that could affect sound. Add to this
the fact that there was no practical way of
adjusting bias in this fixed-bias amp and you
could end up with two amps that looked the
same but sounded very different.
When Fender set out to make this ’ 57, they
picked one particular amp that was admired
by many top players and measured all the
circuit parameters of that amp. They then
used tighter-tolerance components and
handwound transformers that individually
tested to spec in order to replicate the
sound of this amp.
