Marshall JMP 1964 Lead & Bass - High Treble preset

Verified · 88/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The JMP 1964 Lead & Bass is a two-channel EL34 head, also built as the 2100 combo. Four inputs feed both halves of an ECC83, each channel with its own volume, mixing into a second ECC83 gain stage and cathode follower that drives a treble, middle and bass stack. A long-tail ECC83 inverter with presence control pushes two EL34s off a solid-state rectifier and choke. Built to handle guitar or bass, it gives a loud, full JMP-era crunch.

• Made in: UK
• Wattage: 50W
• Channels: 2
• Preamp tubes: 3× ECC83
• Power tubes: 2× EL34

Tags: british, vintage, el34, mid-wattage, bass, crunch.

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.