National Aztec preset

Verified · 86/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Aztec is a National-brand guitar amplifier built by Valco of Chicago, the company behind the National and Supro lines, in the octal-valve era. A single input feeds a 6SJ7 pentode gain stage and one Volume control, with no tone control. A 6SC7 twin triode works as a paraphase phase inverter driving a push-pull pair of cathode-biased 6L6Gs, with a 5V4G valve rectifier. The simple, high-gain front end gives a raw, early-breakup sound.

• Made in: USA
• Wattage: 20W
• Channels: 1
• Preamp tubes: 1× 6SJ7, 1× 6SC7
• Power tubes: 2× 6L6G

Tags: american, vintage.

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.