bluefoxicy Posted February 19, 2019 Share Posted February 19, 2019 It occurs to me a 1:1 PT at 50VA costs only $10, while the PT on the Valve Jr costs $35-ish. With about $5 of circuitry, I can build an adjustable boost converter to get 170VDC-550VDC out. I figure $7-$8 will let me pull 5V-15VDC (filament) and 170V-550VDC (tubes), with the high-voltage followed by your standard power resistor layout, unless you want to spend $2.50 on a buck converter for each following stage (the capacitor becomes a filter capacitor). Drop in the $10 transformer and you've got a $20 PSU rather than the $45 one (PT + resistors) everyone uses. Components can be sized for like 300W so you can use a 300VA transformer for ~150W output. You CANNOT run a rectifier tube from the same transformer winding. It won't work. You'll short your amp out. Does that sound like a good piece for a DIY kit? I also want to build an OTL stage for the Valve Jr, but that's not generic. I'd need a different OTL stage for each type of amp, although I guess adjustable impedance matching would let me use the same stage on the same layout. Together that cuts about $50 off the DIY, I think? Quote Link to comment Share on other sites More sharing options...
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.