FEATURE
Shooting for the Moon
The amp business in 1955 was still a fairly
open field. Fender was the leader, but not
yet the all-ruling juggernaut it would become.
Gibson ran a distant second, although it was
introducing new models at a rapid pace.
Smaller brands such as Premier, Epiphone,
Multivox, and Magnatone were either looking
for their niche or rapidly falling behind. While
the majority of amps available on the market
were still relatively small and low-volume,
with minimal features and weak output,
Guild made an attempt to take a place in
the higher end of the market. But while the
new Guilds were built a bit more sturdily than
most amps and offered good controls and
speaker options, they lacked a truly robust
circuit design.
instrument inputs was labeled “Recording,”
and according to the catalog, this input
was modified with a “Filtertone” buffer for
use specifically in recording situations. The
Recording input ran through a separate filter
network and, unlike the two other instrument
inputs, was not wired at the jack with 68k
resistors. Each Masteramp had the same set
of controls: Volume for each channel, plus
master Bass and Treble controls. Also on the
panel were controls for the tremolo feature,
including an on-off slider, knobs for Strength
and Speed levels, and a jack for the optional
trem-control footswitch.
that it had enough voltage to eliminate the
need for a power transformer and allow the
use of a weak (read “cheap”) output transformer. This type of construction would, at
least in theory, lower the price of the amp.
Using the 50L6 involved wiring the filaments
of three tubes in series, creating a trio. The
Masteramp 66 had a single trio of 50L6
tubes. The Double-Twin and 99 had two sets
that ran push-pull. The Double-Twin also used
dual selenium rectifier units that are similar to
today’s diode rectifier. Preamp tubes on all
three were 12AX7 and 6SN7.
The initial line of Masteramps dripped
’50s style, with chunky “TV” front plywood
cabinets and a two-tone vinyl covering of
fabric-textured tan on top and dark faux
wood grain on the bottom. Staying to the
industry-standard price-point formula of low,
medium, and high, Guild offered three models. The smallest of the ’ 55 Masteramps was
called the 66. Standing a foot-and-a-half tall,
the relatively compact 20-pounder offered 15
watts through a single 12" RCA hi-fi speaker.
Next up in size, price, and power was the 99,
a 25-watt amp with a 12" Jensen and two
Jensen tweeters.
From 50L6s (and No Transformers) to 6L6s
Tube selection is where the Masteramp story
gets weird. The catalog mentions that the
66 has a six-tube chassis—RCA tubes at
that. The 99 had a seven-tube chassis, and
the Double-Twin had nine. What the catalog
doesn’t say is that the power tubes on all
three amps are of the 50L6 variety. Mention
the 50L6 to any amp old-timer and they’ll
guffaw and roll their eyes. In the 1950s, the
50L6 was not used as a high-fidelity tube.
Rather, it was used when the goal was to
push volume through a speaker. The benefit
of the 50L6, at least in 1954 and 1955, was
Guild shot for the moon with its top-of-the-line amp, the Double-Twin. It was stocked
with two 12" Jensen P12P Concert-series
drivers and two switchable Jensen 4" tweeters. By adding the tweeters, Guild aimed
squarely for the high-end market. An amplifier with two 12" speakers was big stuff for
any company in 1955, much less a startup.
The few other 2x12 amps of the time came
from major manufacturers like Fender and
Gibson. The 1955 catalog billed the Double-Twin as “perfect for small combos.” That pronouncement may seem odd or obvious unless
you know that, at that time, all the players in
a group usually shared one amp. Guitarist,
singer, and even a string bass player would
plug into the same multi-input amp.
Early Double-Twins featured a nine-tube complement powered by 50L6s, as well as two 12”
In addition to the aforementioned problems
with 50L6 tubes, heat issues were a real concern. Today, many amps that came equipped
with 50L6 tubes show signs of heat damage
to the chassis. Guild certainly became aware
of the issue, because at a certain point during
the run of the first Masteramp series, 50L6s
were ditched in favor of the more stable,
more powerful, and—above all—more musical 6L6. While the transformerless 50L6 circuit
was a money-saver early on, glass-tube 6L6
and 6V6 tubes were rapidly coming down in
price enough to make up for the expense of
a power transformer. It was an added bonus
that these tubes also offered a much more
Each of the three ’ 55 Masteramp models
had top-mounted controls on a chrome
panel with screened white lettering. They
all had two channels, with a single input
for the Accordion/Mike channel and three
inputs for the Instrument channel. One of the
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