Valco 6143 preset

verified · 90/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Valco Model 6143 is a tiny transformerless-style student amp of the late 1950s and early 1960s. Two inputs feed both halves of a single 12AX7, with a Volume control between the stages and a simple treble-cut Tone control, driving one 50L6 beam tetrode single-ended into a 3.2-ohm speaker. A 35Z5 rectifier runs straight off the mains (no power transformer); 35W4 is shown as an alternate.

• Made in: USA
• Wattage: 4W
• Channels: 1
• Preamp tubes: 1× 12AX7
• Power tubes: 1× 50L6

Tags: american, vintage.

Schematic-derived preset files for the Neural DSP Quad Cortex and 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.