Marshall Amplifiers

After a successful career as a drummer and teacher of drum technique, Jim Marshall first went into business in the early 1960s with a small shop in Hanwell, London, selling drums, cymbals and drum-related accessories; Marshall himself also gave drum lessons. According to Jim, Ritchie Blackmore, Pete Townshend and other guitarists often came into the shop and asked why Marshall was not selling or producing guitar equipment. Marshall Ltd. later expanded and started selling guitars and amplifiers, the most notable of which at the time were the Fender amplifiers imported from America. These were very popular with guitarists and bass players, but were very expensive.

Jim Marshall thought he could produce a cheaper alternative to American-made guitar amplifiers, but he had limited experience as an electrical engineer. He enlisted the help of his shop repairman Ken Bran and an EMI technician named Dudley Craven, and between them they decided they most liked the sound of the 4x10" Fender Bassman. They made several prototypes using the Fender Bassman amp as a model. The sixth prototype produced, in Jim's words, the "Marshall Sound".
The first few production units almost copied the Bassman circuit, with American military surplus 5881 power valves, a relative of the 6L6. Speakers were then rarely able to handle more than 15 watts, which meant that an amplifier approaching 50 watts had to use four speakers. For their Bassman, Fender used four Jensen speakers in the same cabinet as the amplifier, but Marshall chose separate amplifiers from speaker, and placed four 12-inch Celestion speakers in a separate closed-back cabinet instead of the four 10-inch Jensens in an open-back combo. Other crucial differences were the use of higher-gain ECC83 valves throughout the preamp, and the introduction of a capacitor/resistor filter after the volume control. These circuit changes gave the amp more gain so that it broke into overdrive sooner on the volume control than the Bassman, and boosted the treble frequencies. This new amplifier, tentatively called the "Mark II", was eventually named the "JTM 45," after Jim and his son Terry Marshall and the wattage of the amplifier.

Marshall has celebrated over 25 years of manufacturing one of the most coveted brand names in amplification history.
See my links below for a more in depth look into the history and heritage of Marshall Amplifiers.