[The vacuum tube is back.][1] Interestingly, vacuum tubes offer two advantages over their successor the transistor: they are faster, because electrons move more quickly in a vacuum rather than through a solid, and they are more resistant to external radiation.

But can you still get that humming overtone in guitar amps?

[1]: http://news.sciencemag.org/sciencenow/2012/05/return-of-the-vacuum-tube.html