Davoli UP4 Power Unit (EL504) preset

Verified · 82/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The UP4 is a Davoli power unit with a transistor input stage feeding an ECC82 long-tailed-pair inverter and a pair of EL504 TV line-output tubes with adjustable fixed bias. It has no tone controls and was paired with a separate Davoli preamp.

• Made in: Italy
• Channels: 1
• Preamp tubes: 1× ECC82
• Power tubes: 2× EL504

Tags: italian, vintage, hybrid, power-amp.

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.