Gibson GA-77RET - Channel I preset

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

The GA-77RET is a 1960s two-channel Gibson combo, two inputs per channel, each channel with loudness, mid-range, bass and treble, plus a jazz switch on channel 2. It feeds a built-in echo/reverb Memory unit with a three-way mode switch and level control, and a photocell tremolo has depth and frequency. A 6FQ7 inverter drives fixed-bias push-pull 6L6GCs on a solid-state rectifier, into a 15-inch or two 10-inch speakers.

• Made in: USA
• Wattage: 35W
• Channels: 2
• Preamp tubes: 3× 6EU7, 2× 12AU7, 1× 6FQ7
• Power tubes: 2× 6L6GC

Tags: american, vintage, clean, reverb, tremolo, 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.