Old public address system tube amplifiers were often very similar to guitar amps, needing only slight tweaking to turn them into guitar amps. Or, if they’re not suitable, they can provide power and output transformers for building a new circuit in the old shell.
I took a Precision Electronics PA-20 amp and turned it first into an AX84 High Octane, then a Marshall 18-Watt circuit, then a 6BM8 circuit based on the 18-watter.
Sub-miniature tubes, also referred to as pencil tubes or hearing-aid tubes, are among the last generation of vacuum tubes designed and built. They’re typically very small, and instead of being socketed they have flexible leads like passive components. Some are designed to be run off of batteries (the hearing aid tubes), with very low heater & B+ voltages, while others were designed for military & industrial use.
The Micro Champ was my second amp build, after the Moonlight. Its initial goal was to build a 1W amp with a basic preamp and a power section using the 6AK6 miniature power pentode. I succesfully built an initial version with a blackface Fender Champ preamp and a single-ended 6AK6. That’s where the name came from.
The Moonlight, a 1-watt amplifier designed by Simcha Delft, was my first amp build, and responsible for getting me hooked on this hobby. I’ve since re-built my Moonlight 3 times in a variety of configurations.
This is another conversion. This time it began life as a Heathkit CB-1 Transceiver. The name of this amp, Lunch Box, comes from the fact that the CB-1 was in a case affectionately called the “lunchbox”, because it looks like, well…a lunch box.