Fender Bassman 5F6-A preset

Verified · 92/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Fender Bassman 5F6-A is arguably the most influential guitar amplifier circuit ever designed — a 45W tweed head with four 6L6 output tubes, two channels, and a long-tailed-pair phase inverter that became the direct template for the original Marshall JTM45. Although designed for bass, guitarists quickly discovered its open, harmonically complex overdrive character, and it has been revered and cloned ever since. The JTM45 designation in the filename refers to the fact that this schematic documents the Fender circuit that Jim Marshall directly copied.

Known for: Keith Richards, Eric Clapton.

Tags: american, crunch, vintage.

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.