FEATURE
openings. Gibson would later realize that
this type of speaker opening restricted
speaker output and change to an open-grille format. The cabinet itself was large,
a full four inches deeper than the next
largest Gibson, the GA- 75. While many
of the Class of ’ 48 Gibsons were shallow rectangles resembling suitcases, the
GA-CB seems almost a cube. The extra-deep cabinet somewhat resembles a late-
‘40s Jensen Imperial Hi-Fi speaker, and it
provides ample room for the brown-frame
15” Jensen Concert Type H Coaxial driver,
of which Gibson claimed a “ 50 to 15,000
cycle range.” Incorporating a tweeter unit
mounted inside the woofer, the Type H
speaker was designed for use in Hi-Fi stereo systems. McCarty and Lover were well-known Hi-Fi buffs and considered what
was good for Hi-Fi to be good for guitar
as well. This attitude is further in evidence
by the presence of a Jensen four-position
High Frequency Control unit located at
the upper back of the GA-CB. The rotary
control has four positions, at 10, 11, 1 and
2 o’clock (although it will hold at the 12
o’clock position as well).
Also offered on the higher-end models of Jensen home speakers, the High
Frequency Control served to either impede
or free the flow of upper-frequency signals
to the driver. Coming in at 60 pounds, the
GA-CB is fully double the weight of the
GA- 75. The added weight is a product of
the heavy-duty driver, the larger chassis,
the sturdy transformers, and the obvious
heft of the cabinet wood.
In design, construction, price and tone,
the GA-CB was beyond almost any other
amplifier of the time. In fact, the GA-CB
may have been the most advanced guitar
amplifier of the early 1950s. In comparison to the Fender Pro, an amp that also
featured dual 6L6 power tubes and a 15”
speaker, the GA-CB has more power, more
features and a higher-quality driver. Where
the Fender beat the Gibson hands-down
is in its guitar-specific voicing. Fender
had learned that players were looking for
a new, unique tone, something different
from the sounds of the ‘30s. Gibson hadn’t
gotten this message yet. While they may
have been building higher-end amplifiers,
they still had not moved significantly away
from using lightly-modded PA circuits for
their guitar amplifiers. Additionally, the
entire Gibson team ascribed to a sound
ideal that was smooth, mellow, and, above
all, 100 percent distortion-free.
With the combination of higher power, a
tremolo circuit, and the Jensen-designed
High Frequency Control, Gibson offered
with the GA-CB a package aimed squarely
at the professional player. In advertisements of the time, Gibson touted the
Photos: Lynn Wheelwright
GA-CB as being “superlative for studio
work, for church or auditorium use.” Cleary
not an amp for greasy kids, twanging cowboys, or hard blues. By the end of its production run in 1953, only 108 GA-CB amps
had been built. At $425 the GA-CB was a
very expensive piece of equipment. Using
the Consumer Price Index calculator, the
GA-CB would cost today roughly $3835,
a price similar to some of the currently
available boutique, custom and high-power amplifiers. As for finding an actual
GA-CB, few are known to exist. Even
major collectors just shake their heads
“no” when asked if they have a Custom-Built. Some recall an opportunity to buy
long past, but most have never even seen
one. The amplifier shown in these photos
belongs to the collector and historian Lynn
Wheelwright. Lynn found this amp online
about ten years ago. A clean example
such as this is almost unheard of, so it is
an added bonus for gear fans that this
particular amplifier will be on display at
the Museum of Making Music in Carlsbad,
CA, through March, 2010, as part of the
exhibit: ON! The Beginnings of the Electric
Sound Generation.
Wallace Marx Jr. is the author of Gibson
Amplifiers, 1933-2008: 75 Years of
the Gold Tone.
