Guyatone GA-820 preset

Close · 76/100 confidence. Most values readable. Minor gaps filled by inference from similar circuits.

The GA-820 is a single-channel Guyatone combo from Japan with two inputs, passive treble and bass, and volume. Half a 12AX7 is the input stage; 12AU7s provide gain, a split-load inverter and push-pull drivers for a fixed-bias pair of 6BQ5 (EL84) tubes. The other 12AX7 half runs a tremolo with speed and intensity and a footswitch, and a 12AU7 drives the spring reverb through a transformer, recovered by a 6AU6 with a reverb level control.

• Made in: Japan
• Channels: 1
• Preamp tubes: 1× 12AX7, 3× 12AU7, 1× 6AU6
• Power tubes: 2× 6BQ5

Tags: japanese, vintage, clean, reverb, tremolo, el84.

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.