Marshall Amp Identification: 1967–1980 — The JMP Era

I compiled this chart throughout years of combing through examples on the work bench, in shops across the US and UK, and examples found in forums online. The year markers are not absolute. Marshall would use parts until they were gone. There are also more oddball examples in different markets across the globe. These findings are based on the two largest markets which were the USA and UK.

Some things not listed in the graphs were front panel features like polarity switches that were present on USA market amplifiers until 1974.

Remember, the most consistent thing is inconsistency!