Sunn Coliseum 300 preset

Verified · 88/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Coliseum 300 is Sunn's mid-1980s solid-state bass head from the Fender-owned era of the company. One channel with Normal and Brite inputs feeds an op-amp preamp with Gain, a VCA-based compressor (Compression control and in/out switch, with LED indicators), a Contour switch and a graphic equalizer on slide controls, then a Biamp crossover control and Master. Biamp and line jacks sit ahead of a high-power transistor output stage built on its own power board.

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.