Gregory Mark X preset

Verified · 93/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Mark X is a small single-channel Gregory amp with three inputs (one low, two high), volume and a treble-cut tone control. One 12AX7 provides two gain stages with feedback from the speaker; half of a second 12AX7 is a paraphase inverter and the other half a phase-shift oscillator that modulates the output bias for tremolo, with speed, strength and a footswitch. A cathode-biased pair of EL84s gives about 10 watts on a 6CA4 rectifier.

Tags: vintage, el84, tremolo, low-wattage.

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.