Marshall amps began featuring aluminum back panels in 1969.
I won’t write the rest because it may confuse you even more. It’s important to note that, for example, a 1959 amp has nothing to do with the The JTM-45 JTM-45 with “block” logo The first Marshall ever made. The front panel has “Presence”, “Bass”, “Middle” and “Treble” controls, as well as 2 volumes and 4 inputs.
It was basically a copy of the 1959 Fender Bassman. In 1965, the plexiglass faceplates were introduced.
First, it will be useful to you to understand the following five terms in order to choose the correct chart for dating your amp: refers to the two-tone woven fabric that covered many early amplifiers.
On early amps, this material was varnished to make it a more durable covering.
Note that some models produced from 1979-81 had serial numbers stamped on the front panel (to the left of the power switch).
How to read the serial number (1969-1983) Marshall used a coding system that provided (a) model, (b) serial number, and (c) manufacture date.
Before starting, I must warn you that acquiring vintage gear can be really risky.
You can end up buying something that is not what you expected or even something that is damaged or modded beyond repair.
So, always keep your eyes open for “fishy” deals, look for information, and always ask for high definition photos (especially from the interior of the amps – the circuit, the tubes and transformers) to make sure everything is right.
If you don’t have much experience (myself included, to be honest : P), I recommend asking help from the members here of the community.
Compared to the earlier "Master Volume" series, they offered some advantages, including the possibility to be patched internally and linked with other amplifiers.