Ampeg AP-3550 Power Amp preset

Close · 60/100 confidence. Most values readable. Minor gaps filled by inference from similar circuits.

The Ampeg AP-3550 is a solid-state rack power amplifier from Ampeg's early-1990s St. Louis era, rated at 350 watts. It has no tone stack: its control board carries an NE5532 op-amp input stage with a Volume control whose pull switch defeats the limiter, a Presence control, a limit indicator and an LM3915-driven LED output meter, ahead of a transistor power stage meant to be paired with a separate bass or guitar preamp.

Tags: american, bass, solid-state, high-wattage.

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.