What tubes does the Marshall JMP 1987 Lead 50 (1968) - High Treble use?

The Marshall JMP 1987 Lead 50 (1968) - High Treble uses 3× ECC83 preamp tubes and 2× EL34 power tubes.

When was the Marshall JMP 1987 Lead 50 (1968) - High Treble produced?

The Marshall JMP 1987 Lead 50 (1968) - High Treble was produced 1967–1969.

Marshall JMP 1987 Lead 50 (1968) - High Treble preset

Verified · 86/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

This 1968 Model 1987 is the 50-watt plexi-panel Lead head, the two-valve-output counterpart of the 100-watt 1959 Super Lead. Four inputs into two ECC83 channels, each with its own volume, mix into a second ECC83 gain stage and cathode follower driving Treble/Middle/Bass, with a long-tail ECC83 inverter and Presence. No master volume; silicon diodes and a 20H choke supply the HT, for a looser, earlier breakup than the 100-watt head.

Years produced: 1967–1969
Made in: UK
Wattage: 50W
Channels: 2
Preamp tubes: 3× ECC83
Power tubes: 2× EL34

Tags: british, vintage, plexi, crunch, el34, mid-wattage, two-channel.

Schematic-derived preset files for 16 Fractal and Line 6 modelers: Axe-Fx II/XL/XL+, Axe-Fx III, FM3, FM9, and the full Helix family (Floor, LT, Rack, HX Stomp, HX Stomp XL, Native).

Gridleak extracts amp parameters from original circuit schematics using AI vision — component values, gain staging, tone stack topology, tube types — then generates native preset files for every supported modeler. Every extraction is scored 0–100 and the score is published.