After fifty years since its creation, the Marshall JTM45 remains both a relevant and near-perfect example of what a great rock ‘n’ roll tube amp should be.
It was originally built around the design of one of Jim Marshall’s favorites, the Fender Bassman. In 1965, Clapton found himself the featured guitarist in John Mayall and the Bluesbreakers. Armed with a 1960 Gibson Les Paul and the Marshall Model 1962 combo amplifier, he single-handedly discovered a combination of guitar and amp that produced an extraordinary howl -- Clapton achieved his trademark sound by playing the amplifier at full volume. The sound was full-bodied, authoritative, but not overly distorted; it easily cut through the other band instruments. The sustain was pure, the treble notes sang and the bass registers exhibited a "throaty" bottom. At such high volumes, the amp was prone to feeding back, and this provided an awesome effect to the overall sound.
The JTM 45 was first built in 1962, handmade in an all-aluminum chassis, by Ken Bran and Dudley Craven. Because of its power, Marshall decided early on to build it as a head, with a separate 4x12" cabinet with Celestion speakers. The amplifier itself was based on the Fender Bassman. It uses KT66 vacuum tubes or valves (though early versions had used US 5881, a version of the 6L6) in the output stage, and 12AX7 tubes (known in Britain as ECC83 valves) in the pre-amplification stage.
Significant differences between the Bassman and the JTM include the all-aluminum chassis (it is less susceptible to hum than a steel chassis), a 12AX7 valve as the first in the chain (the Bassman has a 12AY7), the Celestion speakers with a closed cabinet (compared to open-backed Jensen speakers), and a modified feedback circuit which affects the harmonics produced by the amplifier. As Ken Bran later said, "The JTM also had different harmonic content, and this was due to the large amount of feedback I had given it." The amp was also available as a bass (which lacked a "bright" switch) and a PA version.
By the mid 1960s, the JTM 45 had become so popular that it began to supplant the ubiquitous Vox amps, even their AC50, though it was just as powerful.
In late 1965, Marshall introduced its now standard script lettering, in white, and by early 1966 it began calling the amplifiers "JTM 50". Some 100 early models had red lettering; these are especially collectible. Other cosmetic changes included a gradual switch to different knobs. The JTM 45 became the basis for many subsequent Marshalls, most notably the Bluesbreaker. It ceased being produced in 1966, but was reissued in 1989, though with a modern printed circuit board and 6L6 valves.
The Marshall Bluesbreaker is the popular name given to the Models 1961 and 1962 guitar amplifiers made by Marshall from 1964/1965 to 1972.
The Bluesbreaker, which derives its nickname from being used by Eric Clapton with John Mayall & The Bluesbreakers, is credited with delivering "the sound that launched British blues-rock in the mid-1960s." It was Marshall's first combo amplifier, and was described as "arguably the most important [amplifier] in the company's history" and "the definitive rock amplifier."
According to the most widely accepted story, Eric Clapton wanted an amp that would fit in the boot of his car, so he asked Jim Marshall (whose store in London he frequented) to make him a combo amp powerful enough to use on stage. According to Robb Lawrence's The Early Years of the Les Paul Legacy, Jim Marshall initially gave Clapton a Model 1961 with 4x10" speakers, which was soon replaced with a 2x12" Model 1962. Clapton used the combo amplifier with his 1960 Gibson Les Paul Standard, allegedly in combination with a Dallas Rangemaster Treble Booster, which resulted in the creation of a texture of sound that would become regarded as iconic in the realm of blues oriented rock.
Marshall's Model 1961/1962 combo amplifier entered the market at an affordable price–one third cheaper than a Vox AC30 and half the price of a Fender Bassman combo. Its reputation was cemented when Clapton, who had rejoined John Mayall & the Bluesbreakers, used one to record Blues Breakers with Eric Clapton–a set of sessions now widely regarded as "historic". After that, the combo became known as the "Bluesbreaker." The model was discontinued in 1972.
Marshall's original Model 1961 and 1962 were basically JTM 45 combo amplifiers. Model 1961 was essentially the lead version of the Model 1987 JTM 45, fitted with tremolo and installed into an open backed speaker cabinet, while Model 1962 was the bass version of the JTM 45 (Model 1986), also fitted with tremolo and open backed cabinet. These amplifiers both feature the basic JTM 45 modified Fender Bassman circuit, which provided the origin of what became known as the "Marshall sound". The first versions of these combo amplifiers were made in 1964-1965, with Models 1961 and 1962 being fitted with 4x10" and 2x12" Celestion speakers respectively. An extremely rare 2x12" extension cabinet was also offered. A later model had a slightly thinner cabinet with different acoustics. Production JTM45 amplifiers used KT66 output tubes, which are credited with providing "a round, bell like tone with soft distortion character." Also contributing to the overall sound picture of the JTM45 series amplifiers was a GZ34 rectifier tube.
This Bluesbreaker amp is in perfect condition and has an incredible sound. For more comfort when playing the original knobs have been temporarily replaced by other knobs. The original speakers have been replaced with period correct ones.