This is the Rev. 8 PCB for the Firefly 12AX7 amplifier. These are professionally made, double-sided, drilled boards with plated through holes and silk-screening on the top. The PCB is approximately 6" x 3 1/4".

Download the Firefly PCB Assembly Guide and Bill of Materials: Firefly PCB Build Guide and BOM

Mouser Parts List (updated 25 April 2023). Mouser now carries the recommended chassis and I've included it in the parts list. Note that the guide says a 12x6x2 chassis was used but this was a typo. 10x6x2 is the correct size shown.

The chassis can also be ordered from tubesandmore.com if you are placing an order for the other parts in the BOM (transformers, tubes, sockets, etc). The part number is P-H1444-16.


Jan.2016: I have slightly modified the pot mounting holes to accommodate wiring non-pcb mount pots.

Notes from builders
Chris H: "I swapped the Hammond 125A (output transformer) for a MPS OT5PP because it gave a fuller sound and improved bass response. I was able to play my 5 string active bass with this configuration and it sounded very nice using the OT5PP. With the active bass, the Hammond just wasn’t up for the task. An additional change I’ve made is to swap the 12AU7 for an ECC99 (with R13 being changed from 430 ohms to 220 ohms by means of a DPDT switch added to the chassis). Seems like that gives me a little more headroom prior to breakup on the bass, and it makes guitars pretty loud too."