Gibson GA-77 - Channel 1 preset

Verified · 88/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The GA-77 is a mid-1950s two-channel Gibson combo with bass and treble controls. A 12AY7 input stage, 12AX7 preamp and 12AU7 long-tail phase inverter drive a push-pull pair of 5881s on a 5V4G rectifier for about 25 watts.

• Made in: USA
• Wattage: 25W
• Channels: 2
• Preamp tubes: 1× 12AY7, 1× 12AX7, 1× 12AU7
• Power tubes: 2× 5881

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.