Jackson Ampworks Britain 4.0 - 12AX7 preset

Verified · 90/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Britain 4.0 is a boutique head from Dallas builder Jackson Ampworks with two separate inputs and preamps. One runs an EF86 pentode into its own bass, treble and volume; the other uses 12AX7 stages with its own volume, bass and treble plus a relay boost. Each preamp has its own effects loop before a 12AX7 long-tailed-pair inverter. A rotary switch selects 50 or 25 watts from two EL34s, or 30 watts from four EL84s.

• Made in: USA
• Wattage: 50W
• Channels: 2
• Preamp tubes: 1× EF86, 3× 12AX7
• Power tubes: 2× EL34 (or 4× EL84)

Tags: american, boutique, el34, el84, crunch, two-channel, mid-wattage.

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.