How to Order


I'm sold out of boards!


If there is interest, I may do another run of boards late 2008. Email me at the address below if you want to be notified. They'll likely cost about $25.


Firefly PCB

 

What is the Firefly?


A web site called AX84.com was set up as a tube guitar amp cooperative. The site has dozens of open schematics designed, tested and refined by those that frequent AX84.com.


One of the smallest of the guitar amplifiers is called, understandably, the Firefly.  It is a small (around one watt) tube-based guitar amplifier using three inexpensive and readily available vacuum tubes.  The entire amp can be built for less than $200.


For simplicity it has no tone controls — but does have a selectable “boost” circuit that adds additional gain and overdrive to the little amp.


Matched with a small speaker, this amp makes a fun practice amp and an excellent first tube amplifier project.



 

The Firefly PCB


I initially designed a PCB (printed circuit board) for the Firefly because I am attracted to the neatness and speed with which you can build a circuit using a board.  There are builders who can lay out very neat point–to–point circuits but it does take more time and a good deal of experience.


To build a PCB-based Firefly amp, you’ll need the Firefly PCB which I sell here as well as about $150 worth of parts from two suppliers.  I don’t sell complete kits on this site, only the PCB!


• Download for free the assembly guide (below) which also includes a detailed bill of materials (BOM).

• Order the parts listed in the BOM (I give part numbers for Mouser and Antique Electronics).

• Order the Firefly PCB (right here).


That’s everything you need (except tools and chassis) to build your Firefly guitar amplifier.


The PCB is a professionally made, double-sided, drilled board with plated through holes and silkscreening on the top. The circuit board is approximately 6" by 3 1/4".

Download


Click to download the assembly guide (contains bill of materials):

Click on an image for a larger version.

Site last updated: June, 2008

The hardware is “open”. If you want to modify the original PCB, the file is here. It requires ExpressPCB’s free software to view or edit (unfortunately their software is Windows only).