About
I needed a practice amp and I knew I wanted something tube-based without any fancy bells or whistles. For that matter, all I really needed was a power amplifier that I could feed pedals into to shape whatever sound I want. After some exploring, I found myself drawn to something like a Gibson GA-5 or a ’57 Fender Champ since both have practically non-existant preamp stages (when it comes to coloring the sound) and a single knob for volume.
I happened to have a bunch of spare parts laying around minus a chassis, some tubes, transformers, and other bits of simple hardware. I was able to score a schematic for a GA-5 and the harder-to-find electrical components I needed from Mojotone. Everything else was either already on-hand or easily procured from hardware shops around Toronto.
Specs for nerds:
Preamp Tube: 12AX7
Output Tube: 6V6GT
Rectifier Tube: 5Y3
Power Transformer: Tweed Champ 5F1 Power Transformer
Output Transformer: Blackface Champ Output Transformer 125A35A
For a 5W Amp this thing rips, especially when hooked up to the matching amplifier cabinet I built. I also ended up adding a guage to the instrument inputs to gauge the level of the input signal when feeding pedals into the amp. Because there is still a very minimal preamp stage in this amplifier, it is possible to unintentionally create some breakup if a signal comes in too hot. The gauge allows for a bit more control of that feature.
Process Documentation
