A great-sounding, professionally serviced 1974 Marshall JMP 50 retaining its original Drake transformers and choke.
This player-grade vintage Marshall combines the classic four-input Model 1987 circuit with a practical pre-phase-inverter master volume, making it easier to use in the studio, at rehearsals and on stage.
ORIGINAL TRANSFORMERS
• Original Drake 1202-164 mains transformer
• Original Drake 784-139 output transformer
• Original Drake choke
MASTER-VOLUME MODIFICATION
A pre-phase-inverter master volume has been installed in the position originally occupied by the power indicator, which has been repositioned alongside it. The modification was inspected and tested during the recent service and operates correctly.
RECENT SERVICE
Professionally serviced by Dave Wittering of Prestige Amp Servicing, a former senior Marshall service engineer. Work included:
• V1 and phase-inverter anode resistors replaced as required
• Phase-inverter anode load resistor replaced
• Bias reservoir and smoothing capacitors replaced
• Screen resistors replaced
• Control pots replaced
• Speaker output sockets replaced
• Marshall-branded ECC83S preamp valves fitted
• Bias set to specification
• Protective chassis earth fitted
• PAT tested
VALVES
Preamp: Marshall-branded ECC83S valves
Power amp: matched Marshall-branded EL34 valves
CONDITION
The original head shell, black covering, feet and cosmetic hardware remain in place. It presents very well for a working amplifier of more than five decades, with small marks, snags and areas of wear to the covering—most noticeably underneath. Please study the detailed photographs, which form part of the description.
The replaced electronic components and master-volume modification are fully disclosed. This is an excellent choice for a player or studio seeking the sound and feel of an original 1974 JMP 50 without the uncertainty of an untouched example.
VOLTAGE & SHIPPING
The mains selector provides 110V, 120V and 240V operation when correctly configured. Collection is welcomed at our Hayes showroom, and worldwide shipping is available in a custom-made Overdrive Guitars carton with substantial internal protection.
Serial number: S/A 6474F
Inspection date: 21 August 1974
