Gibson GA-30 (6SJ7) - Microphone preset

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

This early GA-30 has two channels, each a 6SJ7 pentode with its own volume, mixed into a shared tone control. A 6SC7 serves as gain stage and paraphase inverter for a cathode-biased push-pull pair of 6V6GT tubes on a 5Y3GT rectifier.

• Made in: USA
• Wattage: 15W
• Channels: 2
• Preamp tubes: 2× 6SJ7, 1× 6SC7
• Power tubes: 2× 6V6GT

Tags: american, vintage, clean, 6v6.

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.