Amps from this era still have the block-style Marshall logo and a centered chassis. This era saw the advent of Plexiglas panels (giving rise to the 'Plexi' name) and four-digit model numbers. When did the marshall plexi amp come out?įrom January 1965 to June 1969, model codes were used but no known serial numbers accompanied them. NOTE: Date Code and Serial Number located on the bottom of the back plate. The serial number on a Marshall amp is usually located on the back panel of the chassis but some amplifiers made between 19 had the number on the front panel. Stanmore is the most versatile speaker in the Marshall line-up and is perfect. The letter B was skipped because the letter A was used for 18 months and the letters I, O and Q were also skipped to avoid any confusion being mistaken for numbers. Why is the letter b skipped on a marshall amp? For Marshall amps, pedals or cabinets ONLY. If your enquiry is related to an amp product you own, please include the model and serial number to help us deal with your issue. What do you need to know about marshall amps? Marshall used letters as a date code to represent year of production. They were initially broken down into three parts: the model code, the serial production number and the date code. Starting in July 1969, Marshall starting using official serial codes. Frequently Asked Questions When did they start using serial numbers on marshall amps?