Sound City L/B 120 Mark IV - Brilliance preset

Verified · 85/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Sound City L/B120 Mark IV is a 120-watt Dallas Arbiter head with Normal and Brilliant inputs, active bass/middle/treble controls built into triode feedback loops, presence, and external reverb send/return jacks. Four ECC83s and an ECC81 long-tail inverter drive six EL34s in fixed-bias push-pull from a solid-state rectifier.

• Made in: UK
• Wattage: 120W
• Channels: 2
• Preamp tubes: 4× ECC83, 1× ECC81
• Power tubes: 6× EL34

Tags: british, vintage, el34, high-wattage, crunch, 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.