Metropoulos Forum

What are the key differences between a JTM 45 and a jmp 50? Are the JMP 50's metal panel plexi's? Help???

The JTM45 is the original Marshall. About 30W, KT66s and tube rectifier. They gradually became the JTM50 around 66-67 which became the JMP50 (model 1987) around '68 I think. Roughly with the JMP came the SS recifier instead of tube. JMPs can be Plexi - late 60s - or metal front -69- 70s. Late plexis are basically exactly the same as early metal fronts.

JTM = Jim + Terry Marshall
JMP = Jim Marshall Products
Metroamp = better than modern Marshalls

The major difference is a switch from KT66 to EL34 output tubes. This would imply a change to the output transformer as well since the two tube have different plate resistances. The earlier ones used a GZ34 rectifier tube, but then moved to a solid-state rectifier.