Ampeg Jet J-12A preset

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

The Ampeg Jet J-12-A is a single-channel tube guitar combo, here in its 7591 version. Two inputs feed half a 6SL7 with a volume and a single tone control; the other half of that 6SL7 is the tremolo oscillator with a speed control and footswitch. A second 6SL7 works as a cathode-coupled phase inverter for a cathode-biased push-pull pair of 7591As, with feedback from the speaker and a 5Y3GT rectifier.

• Made in: USA
• Wattage: 18W
• Channels: 1
• Preamp tubes: 2× 6SL7
• Power tubes: 2× 7591A

Tags: american, vintage, tremolo, 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.