this is a re-appropriation of a Fender Frontman 15-B. it’s one 8″ speaker in a closed cabinet primarily designed as a really cheap bass amp to be included in starter packs. having gutted the amp a few years ago and replaced it with the contents from the No. 5 tube amp project, i got some time to rework the circuit into something more usable.
the additions include a tone stack, second gain stage, and a stand-by switch. the power amp is now wired as a pentode instead of a triode, and i didn’t feel it necessary to have a switch between the two modes. it still needs a little work to keep it from self-oscillating at high volumes. thanks to those guys who run AX84.com for their P1 project. it definitely helped the way i thought about redesigning the amp.
and what a lovely voice it is. even through a Crate speaker (i’m saving the better speakers for when the testing phase is over). overall, i’d say a success for cheap transformers, Radio Shack parts, and a few pieces taken from a busted computer power supply.
audio notes: it was late, and i was annoying enough playing at midnight. the mic is sitting just above the speaker which was laying face up in a milk crate. i’m currently using a 100k audio pot, and i think it would fair better with a 1M. overall though, the amp is surprisingly quiet at mid volume. i still need to drill out the hole for AC connector, but it will come in due time. for now, it’s making sound and that’s a huge first step for me.
like Dr. Frankenstein, it’s about time to bring this little fellow to life… or at least try. the schematic i have is a random luck of the draw internet find, and i have no idea whether or not it will work. however, testing will occur on the work bench soon enough to determine what needs to make this single-ended 5watter amplify.