Class A - submini tube amp

grabcad

This is a tiny, all tube guitar amp. The design exists all over the web, but repackaged by me to fit into a Hammond 1590B housing. Output transformer is a Hammond 125A (3 watt, Fender Reverb replacement). The power to the tubes is provided by a switchmode circuit in boost mode. It steps up 12VDC input to about 170VDC. The tubes are both 6021 dual triode subminature. There are 3 gain stages (the first 3 triodes) while the final triode is arranged in single-end topology, biased to 1W. This is plenty (surprisingly) loud for practice, and even recording. It will drive 8 ohm speaker load (try a Marshall 4 x 12 for something really cool, the amp is the same size as a distortion pedal!) It is very crunchy, indeed does not have a clean setting, but the fun is at the other end of the gain spectrum. Final note: this just the main packaging work I did in PTC Creo, in order to properly size everything and make drilling templates for the housing. I did the circuit design in Eagle, and had the boards fabricated at OSHPark.com. I'll update it shortly with final edits and renderings....