Supro 6420-SS Thunderbolt Bass Amp (1965, solid-state rectifier varian preset

Verified · 87/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Supro 6420-SS Thunderbolt Bass Amp with solid-state rectifier is a 1965 variant engineered for the emerging needs of electric bass players while retaining the Thunderbolt's fundamental raw American character. The solid-state rectifier provides a tighter, faster response compared to the tube rectifier version, giving this model more punch and clarity for bass guitar applications. Guitarists have also embraced it for its aggressive, immediate attack.

• Years produced: 1965–1968
• Made in: USA
• Wattage: 35W
• Channels: 2
• Preamp tubes: 2× 12AX7
• Power tubes: 2× 6L6

Tags: american, vintage, bass.

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.