Mesa Boogie Mark IIB - Rhythm preset

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

The Mark IIB is the second revision of Mesa/Boogie's Mark II, built on the Mark I's cascaded-gain concept. A relay switches between Rhythm, with Volume 1, treble, bass, middle, bright and shift switches and Master 1, and Lead, which adds a cascaded stage with Lead Drive and Lead Master. Five 12AX7s cover preamp, reverb, effects loop and phase inverter; an optional graphic EQ, presence, slave out and 60/100-watt switch serve four 6L6GCs.

• Years produced: 1980–1983
• Made in: USA
• Wattage: 100W
• Channels: 2
• Preamp tubes: 5× 12AX7
• Power tubes: 4× 6L6GC

Known for: Prince, Mark Knopfler.

Tags: american, crunch, high-gain, 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.