Oahu 397K preset

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

The 1940 Oahu 397K 'Suitcase' amp was built by Valco to sell with Oahu's lap-steel outfits. Two inputs each get one half of a 6N7 dual triode; the first has a volume control, the second runs at fixed level, and the two mix into a 6C5 triode driver. A single-ended, cathode-biased 6V6G drives a field-coil speaker whose 2.5K field doubles as the filter choke, with a 5Y3G rectifier. There are no tone controls and no feedback.

Tags: american, vintage, 6v6, class-a, low-wattage, clean.

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.