AX84 Firefly-style build
I decided try and make something from all the parts I had lying around from my previous builds. The AX84 Firefly seemed a great place to start – low wattage and simple. [An alternative would have been the BabyPlex, also based on the Firefly, detailed here.] I was looking for something simple to build, sounds good for rock, and I loved the idea of being able to use it as a preamp for another amp – the Firezog mod. I just needed to get a few low cost parts (the OT and VVR components from AmpMaker & the Hammond chassis from BlueBell Audio) to get going.
I chose to use VVR of the entire amp to control the overall volume, in place of a master volume. People complain that even the Firefly is too loud for living room playing – hopefully the VVR will help.
Schematic
Layout
Build Pics
- Printing out the layout, taping it to the chassis to mark the centroids of all the holes needed.
- The holes marked and indicated with circles to aid drilling.
- Doing my best to clamp the chassis while drilling. 1st using a small bit, then bigger step bits as required.
- The IEC connector. 4 holes at the corners, then the marking the lines with a scorer. The Dremel was making slow work of it until I drilled a few intermediary holes along the scored line.
- A bit of filing was needed to get it to size.
- Done! Some deburring needed, and two errors spotted…
- Components dry-mounted to check for clearances etc
- View from outside.
- OT wiring runs
- Heater wiring – straight down the middle
- Power supply done
- B+ nodes in
- Wiring round V1 and V2
- Wiring round V3
- The completed guts
- The control wiring
- More control wiring
- Complete!