Marshall JMP 1987 2-Channel 50-Watt Guitar Amp Head 1971 - Black

A Superb Example of a 1971 Marshall JMP 50 “Small Box” – Hand-Wired, Original Transformers, Plexi Power

Offered here is a truly outstanding specimen of the highly sought-after small box hand-wired 1971 Marshall JMP 50, complete with its original laydown Drake 1202-118 power transformer, Drake 784-139 output transformer, and original choke. Featuring a 50-watt power section that delivers those unmistakable late-Plexi tones, this amp is every bit the powerhouse that built the Marshall legend.

For a piece of gear now in its sixth decade, its condition is remarkable—only the lightest tolex wear on a few corners, with the original black covering, feet, handle, gold beading, and script badge all intact. The hand-wired tag board remains wonderfully original, with many solder joints still sealed in the distinctive red shellac. The only changes are three small service-related capacitors on the board, carefully installed to maintain originality and performance.

It has recently undergone a full workshop inspection and service. Both the ECC83 preamp valves and EL34 power valves have been tested and are performing exactly to specification. The tone? Absolutely what you’d expect from this era—rich, articulate, harmonically complex, and unapologetically aggressive when pushed. In short: the classic Marshall roar, with all the touch sensitivity and dynamic response that makes these amps so addictive.

Other period-correct details remain intact: the impedance selector is original and fully functional, and the amp is currently hard-wired for 220–240V operation, though it can be converted for 115V use in North America. The original Bulgin mains inlet has been replaced with a modern IEC socket for practicality and safety. All capacitors remain original, preserving the amp’s authentic voice.

As confirmed by the inspection sticker still affixed to the chassis, this amp passed its final quality control at the Marshall factory on January 18th, 1971. Serial number: 0222C.

Vintage Marshall collectors and tone connoisseurs will appreciate not just the rarity and originality of this JMP 50, but also the fact that it’s ready to plug in, turn up, and inspire—just as it did over half a century ago.

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