DIY 6V6 Plexi - Normal preset

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

The Plexi 6V6 is a 2008 DIY design by Mark Huss that puts a Marshall Plexi preamp in front of a pair of 6V6s. One input feeds both halves of a 12AX7, with Normal and Bright volumes, a cathode follower into a treble, middle and bass stack, a FAT switch and presence, then a 12AX7 long-tailed-pair inverter and fixed-bias 6V6s. The original runs a diode rectifier and no master; the built version adds a master volume and a GZ34.

• Channels: 2
• Preamp tubes: 3× 12AX7
• Power tubes: 2× 6V6

Tags: diy, british, plexi, 6v6, low-wattage, crunch.

Schematic-derived preset files for the Neural DSP Quad Cortex and 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.