The history of the legendary Marshall 'plexi' amps

About Marshall

In the world of electric guitars, there is no more famous name or more recognizable logo than Marshall. It has become the standard for rock guitar sound for the last 30 years, and the logo and image of the Marshall stack have become cultural icons. Late Jim Marshall, the company founder ran a drum store in Hanwell, London during the early 1960s. He also supplemented his income by teaching drum lessons. Some of his customers including Ritchie Blackmore (Deep Purple) and Pete Townsend (the Who) inquired as to why the shop wasn’t selling or producing guitar equipment. Marshall expanded the store to include guitars and amps, mainly Fenders.

Not much later, Jim Marshall, along with his shop repairman Ken Bran and a technician named Dudley Craven started working on a number of prototype amps based on the Fender Bassman. The first examples of Marshall amps were very similar to the Bassman, but had a different configuration in that the amplifier was in a separate cabinet to the 4 by 12 inch Celestion speakers. The Fender amps contained the amp and speakers in the one cabinet (known as a combo). Originally called the ‘Mark II’, this first Marshall was renamed the JTM45.

A switch in the types of valve used in the Marshall amps resulted in a more aggressive sound which appealed to many young guitarists. Marshall produced a combo amp especially for Eric Clapton, which became known as the Bluesbreaker amp. John Entwhistle and Pete Townsend were fans of early Marshalls but were looking for increased volume. This lead to the development of the 100 watt models and in 1965, the full Marshall stack – two 4 speaker cabinets on top of each other. Marshalls around this time became known as ‘Plexi’s’ due to the gold plexiglass cover. These amps now have significant collectors’ value and have a tone which is considered classic amongst guitarists. The popularity of Marshalls continued to grow, helped by their use by Jimi Hendrix, Cream and Led Zepplin. In the 70's the idea of a ‘wall of Marshalls’ started to take off due to the use of daisy chaining 2 or more amplifiers together by bands such as the Blue Oyster Cult. The Marshall ‘wall’ became a widely used live visual prop for many rock and metal artists such as Slayer, Motley Crue and Yngwie Malmsteen. In reality, most of the cabinets you see in these concerts are actually turned off. Sound at large concerts has to be controlled through a front of house mixing desk so guitar sounds are usually miked from a single or small number of amps then incorporated into the main mix. In the 70's Marshall began producing the MV series amp, which they went on to rename the JCM800. This amp is one of the most famous amps in history, although there were slightly different versions which used different types of valves. This model also introduced channel switching, which meant a guitarist could switch between clean and distorted sounds using a footswitch.

Read more:
At Vintage Guitar Magazine about The birth of Marshall amplifiers.
At Wikipedia about Marshall facts, the Marshall JTM45 (Bluesbreaker) and the Marshall 1959 Super Lead Plexi.