Hiwatt STA250 Slave preset

Verified · 84/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Hiwatt STA250 is a 200-watt slave power amplifier with no preamp, tone stack or master volume, designed to be driven from an external preamp or head. A level control feeds an ECC83 gain stage, then an ECC81 long-tailed-pair inverter drives six fixed-bias EL34s, three per side, into a Partridge TH6500 output transformer with 4, 8 and 16-ohm taps and feedback from the 16-ohm tap. High clean power for large rigs and PA use.

• Made in: UK
• Wattage: 200W
• Channels: 1
• Preamp tubes: 1× ECC83, 1× ECC81
• Power tubes: 6× EL34

Tags: british, vintage, power-amp, el34, high-wattage, clean.

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.