Doug Hammond FireFly preset

Verified · 92/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The FireFly is a 2003 DIY micro tube amp design by Doug Hammond, shown here in its third revision. A switchable cascode boost stage on a 12AX7 (with its own Boost Gain control) feeds a second 12AX7 with a single Gain control, then a 12AU7 wired as a self-splitting push-pull output into a small output transformer. There is no tone stack and no negative feedback; the supply uses solid-state diodes.

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

Tags: diy.

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.