Sunn Spectrum II preset

verified · 90/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Sunn Spectrum II (November 1967 schematic) is a 60-watt single-channel tube head for bass and guitar with no effects. Two inputs feed a paralleled 12AX7 stage and one Volume, then passive Treble, Bass and Contour controls. A 6AN8 pentode gain stage with its triode half as a cathodyne inverter, and feedback from the 16-ohm tap, drives two KT88s in adjustable fixed bias into a 3-60T output transformer, from a GZ34 rectifier with choke and standby. Sunn's own notes list it as discontinued in 1969.

Tags: american, vintage, bass, clean.

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.