Vox AC50 Mk III - Normal preset

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

The AC50 Mk III (drawn as the AC50/4 Amplifier Mk III) is a 50-watt Vox head. Normal and Brilliant channels each have their own input triode on a shared ECC82, their own Volume, an ECC83 gain stage and cathode follower, and their own Treble and Bass; the Brilliant channel adds a Bright switch. An ECC83 long-tailed pair drives two fixed-bias EL34s in Class AB, with adjustable bias, on a silicon bridge rectifier with a choke.

• Made in: UK
• Wattage: 50W
• Channels: 2
• Preamp tubes: 3× ECC83, 1× ECC82
• Power tubes: 2× EL34

Tags: british, vintage, el34, two-channel, mid-wattage.

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.