The Marshall JTM45 is Marshall's first guitar amplifier, prototyped in 1962 and produced from 1963. It was developed as a British alternative to Fender amplifiers, using a modified Fender Bassman circuit with a 12AX7 preamp valve, Celestion speakers in a closed cabinet, and a modified negative feedback circuit that altered harmonic content. Its name reflects Jim and Terry Marshall and its 45-watt RMS rating.
The Marshall Major is a 200-watt guitar amplifier built from 1967 to 1974. It was designed to produce more volume and clean headroom than Marshall's other amplifiers like the Super Lead. The 200 had only three controls on the front panel and used a preamplifier circuit that was closer in design to a hi-fi amplifier rather than a guitar amp. In 1968, Marshall updated the 200 with a typical EQ compliment of treble, middle, bass, and presence controls, and it was now named the Major. This tone stack—which was passive compared to the 200's active controls—was placed between the second and third gain stages created using ECC83 (12AX7) preamp tubes. Ritchie Blackmore of Deep Purple and Mick Ronson of David Bowie's band are frequently associated with the Major.