Sound City L.B120 Mark IV preset

Close · 75/100 confidence. Most values readable. Minor gaps filled by inference from similar circuits.

The Sound City LB120 Mark IV was the company's top-of-the-line amplifier, pushing 120 watts through four EL34 power tubes for massive stage presence. Dallas Arbiter built these amps with quality components and Jim Marshall contributed transformer designs, resulting in a head that competes with period Marshall JMPs in tone and build quality. Its relative obscurity compared to Marshall has made it an underground favorite among tone-chasing guitarists.

• Years produced: 1970–1975
• Made in: UK
• Wattage: 120W
• Channels: 2
• Preamp tubes: 3× ECC83
• Power tubes: 4× EL34

Known for: David Gilmour.

Tags: british, vintage, 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.