Uploaded March 2025 | Updated September 2026, 6 days ago

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I compare two amazing Marshall 50W Lead amps: the 1985 JCM800 version vs the 1973 JMP version. I'm also go through the schematics of both amps looking at the differences. Finally I open up the amps to look at the components. I'm playing both amps through a 1972 Marshall 1960B cab using a Gibson Les Paul R9.

Gear:
1985 Marshall JCM800 50W Lead Model 1987
1973 Marshall JMP 50W Lead MkII Model 1987
1972 Marshall 1960B 4x12 with T1221 Greenbacks (Pulsonic Cones)
2008 Gibson Les Paul R9 (1970s DiMarzio PAFs)
ToneKing Iron Man II -8dB
1960s Sennhesier MD21 mic
Neve 1073DPX Mic Pre


JCM800 1987 schematic: schematicheaven.net/marshallamps/jcm800_lead_50w_1987.pdf

JMP 1987 MkII schematic: el34world.com/charts/Schematics/files/Marshall/Marshall_1987_mkii_jmp_50watt.gif

JMP 1987 MkI schematic: schematicheaven.net/marshallamps/jmp_lead_50w_1987.pdf

Also in this video go through how these amps evolved from the 1959 Fender Bassman:
youtube.com/watch?v=10-gIlQr9ho