Marshall 18W Schematics

In 1965 Marshall introduced the 18W “practice” combo amps. Although they were not very loud, they certainly could rock. There were originally 3 combo models: 1958, 1973 and 1974. They had a tremolo and an optional reverb. These amps used 3x ECC83 in the pre amp, 2x EL84 tubes in the power amp, and an EZ81 rectifier in the power supply. If the reverb was fitted, an ECL86 was used as the reverb drive/recovery tube. These 18W amps were discontinued in 1967, to be succeeded by the 20W Marshalls.

JMP 1958 Lead, 18W 2×10″ combo

Schematic with 3x ECC83, 2x EL84 & 1x EZ81.

Schematic redraw with 3x ECC83, 2x EL84 & 1x EZ81.

JMP 1973 Lead & Bass, 18W 2×12″ combo

Schematic with 3x ECC83, 2x EL84 & 1x EZ81.

Schematic redraw with 3x ECC83, 2x EL84 & 1x EZ81.

JMP 1974 Lead & Bass, 18W 1×12″ combo

Schematic with 3x ECC83, 2x EL84 & 1x EZ81.

Schematic redraw with 3x ECC83, 2x EL84 & 1x EZ81.

You might want to check out Gabster’s Marshall 18W page. Lots of info and pictures here, including a forum.