Ampeg Mercury M-12A - Accordion preset

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

The Ampeg Mercury M-12-A is a two-channel combo with Instrument and Accordion inputs, each with volume and tone. 6SL7 stages feed a paraphase inverter and a cathode-biased pair of 7591s off a 5Y3 rectifier, and a 6SL7 phase-shift oscillator provides tremolo.

• Made in: USA
• Wattage: 18W
• Channels: 2
• Preamp tubes: 3× 6SL7
• Power tubes: 2× 7591

Tags: american, vintage, tremolo, two-channel, mid-wattage.

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.