Univox U-1236 preset

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

The U-1236 is a Univox valve bass head of the early 1970s, not a solid-state amp. Bass, High and Low inputs feed a 12AU7 with a Sharp/Deep voicing switch, then treble, bass and volume controls. A 12AX7 long-tail inverter with negative feedback from the speaker feeds a 12AU7 driver stage, which drives two fixed-bias 6L6GCs at about 660 V from a silicon supply with a standby switch.

• Made in: Japan
• Channels: 1
• Preamp tubes: 1× 12AX7, 2× 12AU7
• Power tubes: 2× 6L6GC

Tags: japanese, vintage, 6l6.

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.