Sunn 100S / Spectrum II preset

Verified · 92/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

This 1969 Sunn sheet covers the 100S+ (the version without reverb or vibrato, built before October 1967) and the Spectrum II, discontinued in 1969. Two inputs feed a 12AX7 with Lo Boost and Hi Boost switches, Volume, Treble and Bass. A 6AN8 gain stage and cathodyne inverter, with feedback from the output, drive two fixed-bias 6550s from a GZ34 rectifier with choke and standby.

Tags: american, vintage, 6550, bass, clean.

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.