What tubes does the Ampeg Gemini I G-12 - Channel 1 use?

The Ampeg Gemini I G-12 - Channel 1 uses 3× 12AX7, 1× 7199, 1× 6CG7 preamp tubes and 2× 7591A power tubes.

Who famously used the Ampeg Gemini I G-12 - Channel 1?

J.D. Simo are among the notable players associated with the Ampeg Gemini I G-12 - Channel 1.

Ampeg Gemini I G-12 - Channel 1 preset

Verified · 92/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Ampeg Gemini I G-12 is a two-channel guitar combo; each channel has bright and normal inputs, volume, bass, treble and an Ultra Hi switch. A 6CG7 drives the echo (reverb) unit, recovered by half a 12AX7 with a Dimension level control, while the other half runs tremolo with speed, intensity and an After-Beat switch; reverb and tremolo are footswitchable. A 7199 phase inverter drives a pair of 7591As off a silicon bridge rectifier.

Made in: USA
Wattage: 22W
Channels: 2
Preamp tubes: 3× 12AX7, 1× 7199, 1× 6CG7
Power tubes: 2× 7591A

Known for: J.D. Simo.

Tags: american, vintage, reverb, tremolo, two-channel.

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.