Marshall Bluesbreaker

[1][7] 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".

According to a 2011 Vintage Guitar article ranking the twenty-five "most valuable amplifiers", the 1966/1967 Bluesbreaker is seventh on the list, with solid original examples fetching prices between US$8,300 and US$10,000.

[7] These amplifiers both feature the basic JTM 45 modified Fender Bassman circuit, which provided the origin of what became known as the "Marshall sound".

[1] Production JTM45 amplifiers used KT66 output tubes, which are credited with providing "a round, bell like tone with soft distortion character.

[2] Marshall also made an 18-watt combo amplifier with 2×10" speakers (Model 1958) that looked like a smaller version of the Bluesbreaker, and is sometimes referred to as its "little brother".

Reportedly, Clapton told the engineer during the Bluesbreakers sessions that he should mic the amplifier from across the room, because he intended to play it as loud as possible.

[17][18] In comparison with the Marshall JTM45 half-stacks of the time, the open-back combo amps had less low and a bit more crisp high-end response, which suits the Les Paul well, especially when recording blues.