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

Verified · 86/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Ampeg ST-22, ST-25 and ST-42 are solid-state amps from 1968. Two transistor channels each have active bass and treble, with vibrato/tremolo and a spring-reverb echo module on separate sub-boards. The ST-42 has extra power transistors.

• Made in: USA
• Wattage: 42W
• Channels: 2

Tags: american, solid-state, vintage, reverb, vibrato, two-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.