Diyaudioprojects feature a DIY tube-mosfet hybrid headphone amplifier. It uses 12AU7 tubes and the IRF510 mosfet. The schematics, and pcb files are available on their site.
The circuit consists of two stages: 1. a common cathode tube volt amp stage (gain), 2. a MOSFET source follower for current gain (with a LM317 regulator used as a constant current source). Since most headphones are less than 50 ohms a little current is necessary to run them efficiently.
Ah, fun projects, i build one once :)
As it’s all class A efficiency is bad but with a headphone it’s not much of a problem.
I built the exact same project about a year ago, the article is quite old, and it is extremely easy to do. It cost me under 60$ to make it. Sound goods, but mine got a lotta noise. I would strongly recommend it to anyone that want to toy around with vacuum tubes !
And get a regulated PSU.
That could look very cool if blended to the cast acrylic linked recently here somewhere =)
cast acrylic would make it very difficult to replace the tube when it goes bad
He He… Repackage this old project then sell it to the “Audiophiles” for $1000+. There are plenty of them out there.
I got a bag of tubes from an old B&W TV but I haven’t been able to figure out what any of the tubes actually do. Whenever I see a tube project I’m checking if I maybe have the tube(s) needed but never got lucky so far :( I’m actually starting to think about either selling them on ebay or giving them to some museum that’s collecting these things.
Just got finished building two of these guys with a buddy. They sound really good and look great glowing on my desk!
DIY Home Audio Project – Tube Amp (http://www.midsouthmakers.org/2012/05/diy-home-audio-project-tube-amp)