Marshall

JMP Model 1986 Bass 50-Watt Head – 1973

The early 1970s represent one of the most sought-after periods in Marshall's history, and this 1973 JMP Model 1986 Bass is a particularly original and well-preserved example. Built during the famed "plexi-to-metal panel" transition era, these amplifiers share much of the DNA that made late-'60s Marshall amplifiers legendary, while offering the reliability and practicality of the early JMP period.

This example carries serial number S/A 4188E and retains its original inspection sticker, with the coveted Rosemary signature and is dated 31st May 1973. Remarkably, the amplifier remains highly original throughout, with virtually all solder joints still retaining their factory-applied red shellac, a detail highly prized by collectors and a strong indication that the amplifier has avoided unnecessary repairs or modifications during its lifetime.

Under the hood, the amplifier retains its original Drake 1202-118 laydown mains transformer, original Drake 784-139 output transformer, and original choke. These are exactly the components players hope to find in a premium early-'70s Marshall, contributing significantly to the rich, dynamic and harmonically complex tone these amplifiers are renowned for.

Cosmetically, the amp remains exceptionally honest and original. The factory headshell retains its original black levant covering, original handle, feet and Marshall logo. It presents exactly as a well-cared-for vintage Marshall should, showing natural signs of age without losing any of its character.

Although designated as a Bass model, the Model 1986 has become a favourite among guitarists seeking the thicker, warmer response associated with many of the greatest classic rock recordings. With its lower-gain preamp structure and huge dynamic range, it excels with everything from blues and classic rock through to vintage hard rock, while also serving as an outstanding platform for pedals.

Specifications

• Marshall JMP Model 1986 Bass
• 50-Watt All-Valve Head
• Manufactured: 1973
• Serial Number: S/A 4188E
• Inspection Sticker Date: 31/05/1973
• Plate Voltage: 449v at idle
• Original Drake 1202-118 Mains Transformer
• Original Drake 784-139 Output Transformer
• Original Factory Choke
• Original Bulgin Socket
• Bulgin power cable supplied with the head
• Marshall-Branded EL34B Power Valves
• Original Factory Headshell
• Original Tolex, Handle, Feet and Marshall Logo
• Original Red Shellac Present on the Vast Majority of Factory Solder Joints
• Original Main Voltage Selector - 110v, 220v & 230v

Condition

A highly original and exceptionally honest vintage Marshall. Both cosmetically and electronically, it remains one of the most unmolested examples we've encountered from this period. The amplifier shows only expected signs of age and use, while retaining an extraordinary level of originality throughout.

Service Work

The amplifier has been professionally inspected and serviced by Dave Wittering of Prestige Amp Servicing, a former senior Marshall service engineer with 15 years’ experience at the Marshall factory and more than 35 years working with valve amplifiers.

The work was carried out sympathetically, with particular care taken to preserve the amplifier’s exceptional originality. Almost all of the factory solder joints remain untouched and retain their original red inspection shellac. The bias reservoir and smoothing capacitors had previously been replaced with good quality parts.

Service work included:

• 2no. OEM Marshall EL34B Valves
• V2 Anode load resistor replaced - 100k 1/2 Watt
• Bias supply resistor replaced - 220k 1/2 Watt
• Bias supply smoothing caps replaced - 707-6408
• Mains & Ohms selectors serviced & tensioned
• Main smoothing caps replaced w/OEM - CAPR-00054
• Dedicated chassis earth added - Safety!
• Full operational and safety inspection - every component is tested!
• Output valves correctly biased and tested
• Amplifier thoroughly tested following completion of the work

The amplifier is performing exactly as it should and is ready for regular studio or stage use.

Worldwide Shipping Available

Every amplifier we sell is thoroughly inspected and professionally packed before dispatch. We ship worldwide on a regular basis using fully tracked and insured UPS and DHL services. Each amplifier is packaged using our custom heavy-duty shipping cartons and internal protection systems to ensure safe arrival.

Overdrive Guitars are Marshall specialists and an Authorised Marshall Retailer. You're also welcome to visit our West London showroom by appointment, where you'll find an ever-changing selection of vintage and modern Marshall amplifiers available to experience at proper volume.