THD BiValve-30 preset

Verified · 93/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The THD BiValve-30 is a single-channel head from THD Electronics that takes 6L6, EL34 or 6550 output valves without rebiasing, with a Hi-V/Lo-V switch. Two 12AX7As give four gain stages: a More/Less input, volume with a Cut switch, passive treble and bass, and an Attitude control. There is no phase inverter: the two output valves run cathode-biased in parallel single-ended class A. A built-in attenuator, effects loop and line out complete it.

• Made in: USA
• Wattage: 30W
• Channels: 1
• Preamp tubes: 2× 12AX7A
• Power tubes: 2× 6L6GC/EL34/6550

Tags: american, boutique, crunch, 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.