Supro 6420-TR Thunderbolt Bass Amp (1965, tube rectifier) - Normal preset

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

The Supro 6420-TR Thunderbolt Bass Amp with tube rectifier is a 1965 variant of the Thunderbolt series, using a tube rectifier for a softer, more saggy response compared to the solid-state rectifier version. Valco produced multiple Thunderbolt variants over the production run, and the rectifier type has a significant effect on the feel and compression of the amp under load. The tube rectifier version is often preferred for its more vintage, organic response.

• Years produced: 1965
• 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.