Gibson GA-400 Super 400 - Channel III preset

Verified · 87/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The GA-400 Super 400 is a three-channel Gibson amplifier, each channel with a 12AX7 input stage and bass/treble tone network. A 12AY7 mixer and split-load phase splitter feed 6SK7 pentode drivers and a pair of fixed-bias 6550s, with a 6BJ8 compressor and a GZ34 rectifier. The preamp and power amp are on separate chassis.

• Made in: USA
• Wattage: 60W
• Channels: 3
• Preamp tubes: 3× 12AX7, 1× 12AY7, 2× 6BJ8, 2× 6SK7
• Power tubes: 2× 6550

Tags: american, vintage, clean, 6550, multi-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.