Gibson GA-88S Stereo Twin preset

Close · 68/100 confidence. Most values readable. Minor gaps filled by inference from similar circuits.

The GA-88S Stereo Twin is a Gibson stereo amplifier with two separate output channels. In its power section each side has half of a 12AX7 working as a split-load phase inverter, driving its own cathode-biased push-pull pair of 6BQ5 (EL84) tubes and its own output transformer and speaker jack. A GZ34 rectifier feeds both, and a four-position function switch selects off, standby, stereo or mono, where mono ties the two sides to one signal.

Tags: american, vintage, clean, stereo, 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.