Gibson GA-55 - Microphone preset

Verified · 86/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The GA-55 is a 1950s two-channel Gibson combo: an Instrument channel and a Mic channel, each with two inputs on its own 12AY7 and its own volume control, followed by shared treble and bass controls. A 6SC7 twin triode works as the phase inverter for a cathode-biased push-pull pair of 6L6GA tubes on a 5V4G rectifier, driving two 8-ohm speakers, with a standby switch.

• Made in: USA
• Wattage: 20W
• Channels: 2
• Preamp tubes: 2× 12AY7, 1× 6SC7
• Power tubes: 2× 6L6GA

Tags: american, vintage, clean, 6l6.

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.