Valco National Dobro Concert Amplifier 400 - MIC preset

Verified · 80/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The National-Dobro Concert Amplifier 400 is an early Valco product from the National-Dobro era, produced for the lap steel and resonator guitar market. These early Valco designs are historically significant as predecessors to the Supro and National brands that defined the company's later output. The MIC channel suggests dual-purpose use for vocals and instruments, typical of the practical multi-use approach of 1940s amplifier design.

• Years produced: 1940s–1950s
• Made in: USA
• Wattage: 10W
• Channels: 2
• Preamp tubes: 1× 12AX7
• Power tubes: 2× 6V6

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.