Gibson GA-77 (1954) - Channel 1 preset

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

The 1954 GA-77 is a two-channel Gibson combo with a 15-inch speaker. Each channel has two inputs into its own 12AX7; channel 1 has volume, treble and bass, channel 2 volume and a single tone control. A 6SL7 adds gain, a 6J5 paraphase inverter drives a push-pull pair of 6L6GA tubes on a 5V4G rectifier for about 25 watts, and a monitor/recording output and standby switch are fitted. The manual pitches it for microphone PA use too.

• Made in: USA
• Wattage: 25W
• Channels: 2
• Preamp tubes: 2× 12AX7, 1× 6SL7, 1× 6J5
• Power tubes: 2× 6L6GA

Tags: american, vintage, clean, 6l6, two-channel.

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.