Dating my marshall cabinet
It was the first Marshall with a solid state rectifier.
Another player that acquired some of those was Eric Clapton, who used them to tour with Cream.
Marshall then “hot-rodded” the JTM-45 using four KT66 and two 50w output transformers to handle the extra wattage. The result was the JTM-45/100 (JTM-100, for short).
With more power tubes, the amp had more headroom, a tighter bass response and more definition.
If you don’t have much experience (myself included, to be honest : P), I recommend asking help from the members here of the community.
Eric Clapton used a JTM-45 combo on the legendary (Now you know why this amp was called “Bluesbreaker” : P) He used his Les Paul through the Normal Channel of the amp. The then “horrible” distorted and saturated sound turned into what we know today as the “rock tone” (maybe not yet… Another example of this amp can be heard on AC/DC’s This is a confusing era, with lots of changes and new models. 😛 The transitition from the JTM to the JMP amps happened, in my view, with three steps.While all those changes happened, new models started being developed to expand Marshall’s catalog.Here are some of them: Marshall Bass and Super Bass Back of a Marshall Super Bass The Marshall Bass 50w #1986 and the Marshall Super Bass 100w #1992 appeared after the change to the EL-34 tubes. These amps were not only stupidly loud, but also really really clean.He discovered that, by playing really loud, it would start to “break up”. The first one was the creation of the first 100w amp.The JTM-45/ 100 (JTM-100) The JTM-45/100 with the “block” logo Pete Townshend and John Entwistle of The Who needed amps that could overpower the noisy and energetic crowds.It was basically a copy of the 1959 Fender Bassman. In 1965, the plexiglass faceplates were introduced.This is the reason why Marshalls of this early era (up to 1968) are known as “Plexis”.The JTM-100, now with four EL-34s too, also gained a proper 100w transformer. It was called Marshall Super Lead 100w #1959 (Although they still didn’t have the “JMP” mark on the front, In my view, this amps are already into the JMP territory, because they have all of the JMP characteristics). This early “Plexi” versions (up to 1968) are really articulate and have a real nice “roar”.This is a photo of a JTM-45/100, but it’s the same headbox used for the early Super Leads Back of a Marshall Super Lead I think you are all familiar with this amp. If you want to hear this amp, listen to any Free live performance.Paul Kossoff was the man who really knew how to use these.When I listen to the album, and I hear the sweet tone of that Les Paul through his Super Leads, I feel I’m in “tone heaven” 😛 The change to the solid state rectifier By late 1966 – early 1967, Marshall stopped using the GZ34 tube rectifier in all the models and started using a solid state rectifier instead.