Mesa Boogie Mark IIA - Lead preset

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

The Mark IIA, sold at first simply as the Mark II, was the first Boogie with footswitchable Rhythm and Lead modes. A relay switches between Rhythm, with Volume 1, treble, bass, middle, bright and shift and Master 1, and Lead, which adds a cascaded stage with Lead Drive and Lead Master. The V1 socket takes a 12AX7 or a Fetron. A 12AT7 drives the reverb; an optional graphic EQ, preamp out/power amp in jacks and a 60/100-watt switch feed four 6L6GCs.

• Years produced: 1978–1980
• Made in: USA
• Channels: 2
• Preamp tubes: 4× 12AX7, 1× 12AT7
• Power tubes: 4× 6L6GC

Known for: Mick Jones.

Tags: american, high-gain, vintage, 6l6, 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.