Marshall Jtm45 Lead 45W preset

Verified · 80/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Marshall JTM45 is where it all began — the first amplifier bearing the Marshall name, introduced in 1962 and closely inspired by the Fender Bassman 5F6-A circuit. Jim Marshall, Ken Bran, and Dudley Craven modified the Bassman topology with British components, including KT66 output valves and a different transformer specification, producing a characteristically warmer and slightly softer sound than the American original. The JTM45 defined British amp tone for a generation, its two-channel layout and plexi-panel aesthetics setting the visual and sonic template that Marshall would refine for the next six decades. Cream-era Eric Clapton and early Pete Townshend stacks were JTM45-based.

• Years produced: 1962–1966
• Made in: UK
• Wattage: 45W
• Channels: 2
• Preamp tubes: 3× ECC83 (12AX7)
• Power tubes: 2× KT66

Known for: Eric Clapton, Pete Townshend, Jimi Hendrix.

Heard on: Sunshine of Your Love — Cream (1967); My Generation — The Who (1965).

Tags: british, crunch, high-gain.

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.