A metal panel Marshall JMP 50W head from 1971. This amp started its life as a PA model (1985), but has been converted to a bass model (1986) specifications - having said that, the differences are very subtle: just a couple of capacitors and resistors. Compared to the '67 JMP and '68 JMP I also have, this baby screams much more aggressively and it breaks up earlier so it might not be my first choice for clean playing - although that's something definitely possible and worth checking out with this amp too. This amp sounds killer with a treble booster - it'll easily cover even the 80's hair metal territory if needed. The electrolytic caps have been replaced and the amp has otherwise been fully serviced in October 2011.
Specifications
Marshall Amps Info & Schematics
s/n: S/A 2396C (June 10, 1971 is written on the inspection tag)