Ampeg ST-22 / ST-25 / ST-42 - Channel 1 preset

Verified · 80/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Ampeg ST-22, ST-25, and ST-42 were a series of solid-state combo amplifiers from the mid-1970s, with the number designating approximate wattage (22W, 25W, 42W). These compact combos targeted practice and small-venue guitarists seeking affordable, reliable amplification with Ampeg's characteristic American voiced tone. The ST series used transistor preamp and power stages in configurations ranging from small practice combos to mid-wattage gigging amplifiers.

• Years produced: 1974–1978
• Made in: USA
• Channels: 2

Tags: american.

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.