Marshall JMP 1987 Hand wired 50-Watt Guitar Amp Head 1973 - Serviced

Marshall

JMP 1987 – 50W Hand Wired Head – 1973

Serial Number: S/A 4140E
Inspection Sticker Date: 29/05/1973 – 29th May 1973

A superb example of a 1973 Marshall JMP 50 Lead Model 1987, presented in very good condition and retaining an impressive amount of its original components and cosmetics.

Hand wired and dating from Marshall's highly regarded early-'70s period, this 50-watt non-master-volume head delivers everything you'd expect from a great vintage JMP — rich, harmonically complex mids, aggressive British crunch and exceptional dynamic response.

The amplifier retains its original transformers and choke, along with original Mullard mustard capacitors dating from 1972 and early 1973. Most of the original solder joints also retain their factory-applied red shellac coating, a particularly desirable detail for collectors and enthusiasts.

A wonderfully original example that's recently been professionally serviced and is ready to be enjoyed.

Chassis & Originality

• Original Drake 1202-118 laydown mains transformer
• Original Drake 784-139 output transformer
• Original choke
• Original Mullard mustard capacitors, dated 1972 and early 1973
• Majority of original solder joints retain their red shellac coating
• Original handwired turret-board construction

Professionally Serviced

Freshly serviced in September 2026 by Dave Wittering of Prestige Amp Servicing, former Marshall senior service engineer.

The following work was carried out:

• Correct screen resistors fitted – 199-1697
• Bias circuit smoothing capacitors replaced
• V1 and phase inverter anode load resistors replaced
• Dedicated chassis earth fitted for electrical safety
• Both mains voltage and impedance selectors stripped, cleaned and re-tensioned
• Both speaker output sockets replaced
• Full professional inspection and testing

The amplifier has been carefully maintained while preserving as much of its original circuitry and character as possible.

Valves

Power Valves: Marshall-branded EL34s

Preamp Valves: Mixed vintage ECC83 / 12AX7 valves, including Mazda and HRS.

Cosmetic Condition

The amplifier is in very good cosmetic condition for its age, retaining an impressive amount of its original appearance.

• Original headshell and tolex
• Original handle
• Original Marshall logo, with some minor damage
• Original feet
• Minor wear to one corner
• Light age-related marks consistent with a 1973 amplifier

Aside from the corner wear and slight damage to the logo, the amplifier has survived exceptionally well for a head now over 50 years old.

Worldwide Shipping Available

All of our amplifier heads are shipped in custom-made Overdrive Guitars boxes, with additional internal protection to ensure they arrive safely.

We generally use UPS for international shipments and have extensive experience shipping vintage Marshall amplifiers worldwide, with regular deliveries to North America and Europe.

We are proud to be an Authorised Marshall Retailer, offering new Marshall equipment alongside our carefully selected collection of vintage and pre-owned amplifiers.

Our dedicated West London showroom is also available by appointment, where customers are welcome to view, test and experience our amplifiers in person.