Here is one of those projects that goes on for years because its just a self indulgence. I guess that's what hobbies are!
The explanation is in the PDF text and I suppose its not quite vintage radio but it does use valves and those new fangled silicon transistors.
It is a Bass Guitar amplifier that I was partial to making back in the 1970's and 80's. I changed from valves straight to transistors with all my music and Pa amps enjoying being able to make equalising panels, mixers, sound gates and studio stuff so much more compact and with better noise figures. This design has 2 things I never got around to making 1/ A hybrid amp with valves to get all the "valve" sound but with a solid state output transformer and 2/ a back loaded folded 8 foot bass bin with the horn port at ear level to deafen the player.
I suppose this really is Vintage stuff and only good for reading about and seeing how I went about the whole thing.
I'll forward a PDF to be attached to this post and hope somebody gets some benefit from it.
Cheers, Fred.

A Valve and Transistor 350 Watt Hybrid Amplifier

Document uploaded.