Gibson
1949 GA-CB
BY WALLACE MARX JR.
other models, produced in part
to draw potential buyers to the
other amps offered by Gibson.
task at Gibson, it was nevertheless treated
it as serious business.
Some amps are
rare. Some amps are crazy-
rare. Gibson’s Custom-Built amplifier, known
as the GA-CB, is a couple of steps beyond
any of that. An epic sound machine and the
flagship of early postwar Gibson amplifiers,
the GA-CB was a classic “halo” product:
an exotic, feature-laden, high-priced offer-
ing standing head-and-shoulders above
Introduced in 1948, the
Custom-Built led the new
Gibson postwar amplifier line
that included the GA- 20,
GA- 25, GA- 50, and GA- 75. At
this time, Gibson was under-
going a complete overhaul
under the guidance of new
president Ted McCarty. The
BR line, a rush introduction
intended to get Gibson
back on the amp market in
the first days after WWII,
was on its way to oblivion,
save for the diminutive,
yet popular, BR- 9. The
new Gibson GA-series
amps were designed by
Seth Lover and Walter
Fuller and, in a first for
Gibson, built entirely at the
Kalamazoo plant (with the exception of
some cabinets built by an outside vendor).
Offering amps was more than perfunctory
for Gibson. The company had been in the
amp business longer than almost anyone
else, since 1933, and considered it a necessary part of the business of selling electric guitars. So although amp production
was, in comparison to guitar, a secondary
The GA-CB was by far the most powerful, sophisticated, and expensive amplifier
Gibson had ever built. It did, however, have
a number of features one might expect
on a pre-war amp. Most noticeable is the
bottom-mounted chassis with rear-facing
controls. This configuration was fine in the
days when players mostly sat down, placing their amps in front of themselves. But
in the late ‘40s, players were beginning to
stand up more during performances, creating demand for easier access to control
panels. In 1948, the GA- 20 and GA- 75 were
Gibson’s only amps to offer top-mounted
chassis with top-mounted controls. The
GA-CB’s heavy-duty chassis held dual-6L6
power tubes that produced a little over 40
watts of power. The rest of the tube complement consisted of two 6J5, two 6S87,
three 6SJ7 and a 5T4 rectifier. Controls
were bass and treble, frequency and intensity for the Lover-designed tremolo circuit,
and individual gain knobs for both the
instrument and microphone channels.
The Custom-Built was covered in brown
leatherette with green fabric pinstriping and a gold Gibson logo. The speaker
opening consists of six vertical slats cut
into the solid front of the cabinet with dia-mond-patterned grille cloth covering the
