Marshall JMP 100 Superlead 1972

Marshall JMP 100 Superlead 1972 Focusrite isa one préamp The 1959 (Marshall's identifying numbers are not years of manufacture), produced from 1965 to 1976 (when it was replaced by the 2203 "Master Volume"),[1] is an amplifier in Marshall's "Standard" series.[2] It was designed by Ken Bran and Dudley Craven after The Who's guitarist Pete Townshend asked Marshall for a 100 watt amplifier.[3] Its output was first channeled into an 8×12″ cabinet, but that single, unwieldy cabinet was quickly changed to a pair of 4x12″ cabinets, 1960a "angled" on top and 1960b "box" on bottom, creating the famous "Marshall full stack".[4][5] The amplifier also came in a PA version and a bass version, the Super Bass.[1] The Plexiglas panel led to the name "Plexi", and while 50-watt models of the time are also called Plexis,[6] the 1959 100 watt model is generally thought of as the "definitive" Plexi.[7] The panels were actually made from much tougher polycarbonate plastic, but to the average American observer, it looked like the more familiar Plexiglas, and the name stuck. In 1969, Marshall replaced the Plexiglas panel with one of brushed black metal with gold aluminum piping.[1] There were other modifications: In 1966, the KT66 tubes of the JTM-models were replaced with EL34. After 1976, the plate voltages were lowered slightly for improved reliability. But during the 1970s, Marshall's increasing exports overseas led to a problem: Often the EL34 tubes would break during transportation, to the point where amps began being shipped from the factory with more rugged Tung-Sol 6550 tubes, which are "stiffer and not as harmonically rich" as the EL34 tubes.[3]