There are a small handful of old tubes that need an impressively low voltage to work, though, and [J.G.] has put a few of them to work in this battery-powered audio tube amplifier. The key to the ...

The idea of putting a tube in a pair of headphones does tend to bring mental images of massive lightbulb-sized tubes to mind, ...

A glance at any outlet through which Chinese modules can be bought will find this type of tube in small audio amplifier projects, and some of them can be astoundingly cheap. When faced with cheap ...

There are a couple of reasons I suspect it's taken this long to see a vacuum tube in a pair of headphones. Tubes are hungry ...