Rivera Knucklehead - Lead preset

Verified · 86/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Rivera Knucklehead is a 1993 all-tube head with two footswitchable channels, each with its own volume, master, bass/middle/treble and pull switches, switched by photocells. A footswitchable Boost and a Ninja boost add more gain for lead sounds. Four 12AX7s make up the preamp and a fifth is the phase inverter, with Presence and Focus controls, an active effects loop and direct out. Four octal output valves are biased for EL34, 6L6GC or 6550.

• Made in: USA
• Wattage: 100W
• Channels: 2
• Preamp tubes: 5× 12AX7

Tags: american, boutique, clean, high-gain, el34, 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.