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Click on the links here to jump directly to the serial number style that matches your instrument: The earliest Marshall amp models did not have model codes or any official serialization, though some models had a simple sequential four-digit numbering system inside the back panel.
For example, the number S/A 8481 E tells us that this is 50W amp (S/A) made in 1973 (E), production number 8481.
From January 1984 to September 1992, the three-part coding was used by Marshall but the date code letter was moved from the end to the middle. This would indicate a 100W Super Lead (SL/A) built in 1989 (X), production number 10059.
The letter B was skipped, as were the letters I, O and Q since they might be confused for numbers.
Use the model codes and date codes below to determine the model and age of your amp.
From January 1965 to June 1969, model codes were used but no known serial numbers accompanied them.