What tubes does the THD Guitarist Bivalve use?

The THD Guitarist Bivalve uses 2× 12AX7 preamp tubes and 2× EL34 power tubes.

When was the THD Guitarist Bivalve produced?

The THD Guitarist Bivalve was produced 1995–2010.

THD Guitarist Bivalve preset

Verified · 80/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The THD BiValve-30 is Andy Marshall's celebrated tube-flexible boutique amp, featured in this Guitarist magazine schematic, which popularized the concept of hot-swappable power tubes in a production amplifier. The BiValve's two channels cover clean and driven territory, with the unique ability to change sonic character by swapping power tube types. It remains a reference design for players and engineers interested in flexible tube amp architecture.

Years produced: 1995–2010
Made in: USA
Wattage: 30W
Channels: 2
Preamp tubes: 2× 12AX7
Power tubes: 2× EL34

Tags: american, crunch, modern.

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.