Marshall Museum --- Mr. T's Collection vol.3

Item #4

MODEL　　　　　　　：JTM45
SERIAL NUMBER ：None
Appears to have been produced around 1963. Mr. T found this amp in an article in a Japanese magazine featuring “Musical Instrument Stores in London.” He dropped a line to the shop on Denmark Street in London and obtained it. At last we can see the “JTM45” logo. The front panel, which is referred to as “the Sandwich Front,” is the third generation of JTM45 amps. The polarity switch disappeared, and Marshall started using “LOUDNESS” instead of “VOLUME.” The sound is very mild. It is almost completely in its original state.

Enlarged photo of the voltage selector on the RS mains transformer. This selector was necessary since there were different voltages in the UK depending on the region.

The inside of the amp. The left jack appears to have been installed afterwards.

The installed valves. From left to right: KT66 power valve, ECC83 pre-amp valve, GZ34 rectifier valve.

The circuit. It is, of course, point-to-point wiring. It is almost completely in its original state. There is no modification.

The inside of the amp. The transformer on the right has a voltage selector on the top. 12AY7 is installed at V2 (the second pre-amp valve from the left). The former owner may have exchanged it to reduce distortion.

To Be Continued....