DIY ThunderTweak HeavyWater preset

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

The ThunderTweak HeavyWater is a DIY micro-amp design. Two 12AX7s form four cascaded gain stages with More, Tone and Some controls, and a single 12AU7 wired push-pull drives a Fender reverb transformer as the output transformer. It makes about 3.5 watts of saturated tube tone at bedroom volume.

• Wattage: 3W
• Channels: 1
• Preamp tubes: 2× 12AX7
• Power tubes: 1× 12AU7

Tags: diy, low-wattage, high-gain, practice.

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.