Sunn 100S / Sceptre / Sentura II preset

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

This schematic covers the later Sunn 100S (with reverb and vibrato, after October 1967), the Sceptre and the Sentura II. Normal and Bright inputs feed volume, bass, treble, contour and a mid-boost switch, with 12AU7-driven spring reverb (transistor recovery) and photocell tremolo; a 6AN8 driver/inverter drives two 6550s from a GZ34 rectifier at about 525 V.

• Made in: USA
• Wattage: 60W
• Channels: 1
• Preamp tubes: 1× 12AX7, 1× 12AU7, 1× 6AN8
• Power tubes: 2× 6550

Tags: american, vintage, 6550, reverb, tremolo.

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.