1967 Marshall JMP-50 Plexi Head


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Super cool, small box Marshall 50 Watt Plexi from 1967. Just back from a service and sounding majestic!

This amp fits into a period of Marshall production where the brand were transitioning from the earlier JTM 45 and JTM50 to the new JMP50 model. Most likely one of the earliest JMPs and dating to the tail end of 1967 this amp is running on EL-34s with a GZ34 rectifier. Drake Output and Power Transformers with 784 139 and 1202 133 source codes respectively. The choke is likewise manufactured by Drake with a source code of 352 114.
Internally steel chassis is in great condition with little corrosion, the factory inspection chart is still present. The Circuit board is the earlier solid red type used by Marshall. During its recent service some the electrolytic capacitors were found to be leaking and have been replaced. The amp had also previously had the bright cap that is wired in parallel with the 470K mixer resistor on channel 1 removed so it has been put back to spec with an original silver mica in its place, along with a 100pF cap on the volume control. The Indicator lamp has been replaced with an amber jewel type. Externally the cabinet is in great condition, there are a few nicks and tears but the levant covering is clean with little wear. The Plexi front and back panels are free from cracks or damage and the rear baffle still has the original Marshall plate pinned to it. The gold piping is intact. The Gold Marshall Logo is the small script version used during this period.

A rare amp for its combination of attributes, one of the last valve rectified 50w Marshalls but one of the earliest JMP amps. Good small box 50w Plexi Marshalls are getting harder and harder to come by and are getting more desirable again. This one has been owned since the mid-seventies by the same player although it hadn't been used in anger for some time. The all important transformers are present and thanks to its recent service its good to go for years to come.

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