Kay 504 preset

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

The Kay 504 is a small Kay tube combo with tremolo, from around 1961. Three inputs feed half a 12AX7, then a volume and a tone control (with the power switch on the tone pot) ahead of the second half. A single-ended, cathode-biased 6V6 drives the speaker from a 5Y3 rectifier. A second 12AX7 runs a phase-shift tremolo with a speed control and an on/off switch on a jack. Simple and quick to break up, with a warm 6V6 voice.

• Made in: USA
• Wattage: 5W
• Channels: 1
• Preamp tubes: 2× 12AX7
• Power tubes: 1× 6V6

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

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.