Univox U-305R - Channel 1 preset

Verified · 85/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The U-305R is a Japanese-built Univox valve combo of the mid-1960s. Two channels, each with Bright and Normal inputs, a 12AX7 triode stage, its own volume and its own tone control, mix into a 12AX7 gain stage and phase inverter. A 6AN8 drives the spring reverb with a 6AV6 recovery stage, level control and footswitch, and a 12AX7 tremolo modulates the output bias. Two fixed-bias 6973s (6CZ5s may be substituted) run from a 6CA4 valve rectifier.

• Channels: 2
• Preamp tubes: 3× 12AX7, 1× 6AN8, 1× 6AV6
• Power tubes: 2× 6973

Tags: vintage, two-channel.

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.