The
BLUESBREAKER:
Revisited
{The Marshall ads below suggested the reissues matched the originals; in
reality, there were significant differences }
1961, was designed for guitar use only. Both
Model 1962 and 1961 were purposely marketed as the British equivalent to the vastly
popular Fender Bassman, and they offered
quite a bargain for British and European
musicians. The Model 1961 retailed for a
scant $165 American dollars and the Model
1962 retailed for $170, while the Fender
Bassman was nearly double at $300. Both
models went into production in late 1964.
before the leather straps would stretch and
break. In early 1965, an improved, single
plastic strap which was stronger and larger
in size replaced the leather ones.
The very first Marshall combos pro-
duced in late 1964 used what was
known as “Vox-style” cooling vents,
which allowed the heat produced by
the transformers and vacuum tubes
to escape efficiently. Two vents were
installed into the top of the cabinet,
similar to the Vox AC30. The vents were
rectangular in shape and had a metal
screen riveted inside.
Cabinet and Construction
The cabinet dimensions for the Model 1962
(2x12 configuration) were 30” wide by 24”
high by 12” deep. The 1961, incorporating
four 10” speakers, maintained square proportions, measuring 28” wide by 28” tall
and 11” deep. The Model 1962’s width is
2” wider and 1” deeper than the 1961”s
to accommodate the dual 12” speakers.
Chassis Electronics and Components
The internal chassis that included all the
electrical components was made of 6061
aluminum sheet metal. Aluminum has
excellent non-sparking and non-magnetic
characteristics, making it ideal for electrical shielding purposes and chassis use. It is,
however, not as strong as steel and would
fatigue and sag under the weight of the
heavy power and output transformers. To
remedy this, cast aluminum end blocks were
riveted inside each end of the chassis to add
strength and rigidity. The chassis were 2. 5”
deep and purchased from a sub-contractor
named Smiths.
Marshall amplifiers would also gain
a reputation for their ruggedness.
Marine ply birch was used for cabinet construction, as the laminated layers
of glued veneer plywood provided greater
overall strength than a singular plank of yellow pine, which was the wood of choice for
Fender amplifiers. These early Marshalls did
not use the “finger-lock”
joints that would become standard on all
Marshall cabinets a few years later.
Marshall cabinets were also visually appealing and had the look of richly appointed furniture. Black PVC (polyvinyl chloride)
material, similar to the General Tire invention known as “tolex,” was used for the
entire exterior of the cabinet. This smooth,
black fabric was different from the black
“Levant” tolex Marshall would use later.
Accenting the cabinets was Marshall’s
elegant grill cloth. The company’s cata-
logue referred to this early cloth only
as, “contrasting speaker grills,” not
actually describing the color or pattern
of the cloth material. However, it was
known as the “white” grill cloth and
had thin, horizontal gray lines run-
ning through it. Also included on the
earliest models were three leather
straps, attached to the top of the
cabinet and similar to the Vox AC30.
These amplifiers weighed in at a
very heavy 70 pounds, and the
sheer weight meant that it wasn’t long
The JTM45 used one circuit board screwed
inside the aluminum chassis, providing a
central platform for the various electrical
components. Prior to 1965, Marshall used
Tufnell perforated circuit boards; from 1965
to 1967 a subcontractor called Heathfield
manufactured the circuit boards, which can
be recognized by the drilled holes on the
solid sheets.
The output transformer was officially known
by Marshall as the “RS De Luxe.” It was
light gray in color, with horseshoe end bells.
The maximum output rating was only 30
watts, and all three transformers used on
the JTM45 – the output, power and choke
– were purchased from Radiospares, an electrical component clearing house.
The first combos produced in late 1964 were
equipped with two GEC (General Electric
Co.) KT66 vacuum tubes. The original design
of the JTM45 called for the Tung-Sol 5881
