Marshall Amps of the 60's and 70's
Marshall's first amp designs were based on the Fender Bassman tube amp chassis. These models produced 45 watts and were designated as the JTM 45 series. The first amp was designed and constructed for Marshall by Ken Bran in late 1962.
Did you know that the original design used a pair of 5881 output tubes? Along with three ECC83 (12AX7) preamp tubes, this model produced such nice distortion that guitarists such as Eric Clapton adopted the Marshall as their amplifier of choice. The JTM 45-powered 2x12 combo "Bluesbreaker" model amplifier is still considered a classic to this day.
Responding to player requests for power power, Marshall introduced the 100-watt amplifier. The first attempt used a quartet of 6V6 output tubes. The second design used four 6L6 (still used in Fender amplifiers) output tubes. The third trial featured KT66 output valves.
Pete Townshend of The Who was one guitar player who was favorably impressed with the Jim Marshall/Ken Bran model 1959 Super Lead amp, which was introduced in 1966. Tremolo was an option on these amps, and if you see a model number prefixed with a "T", that indicates a tremolo-equipped unit. These amps featured four 1/4" front panel input jacks, located at the far right of the instrument panel.
The "Master Volume" amps were introduced in 1975, allowing guitarists to crank up the preamp section while keeping the power amp section down low. This produced a nice growl at lower volumes, although some of the classic Marshall woman tone was lost when the output tubes weren't allowed to work at full volume. Master Volume amps use a pair of 1/4" input jacks at the far right of the front panel.
Aside from the normal black or green-tinted black vinyl, several models were manufactured in custom colors. Fawn (tan), white, purple, and red are some of the colors of amp heads and speaker cabinets that you may find at vintage boutiques. The beautiful fawn 2x12 combo shown above is a fine example.