Half a century ago, vacuum tubes were very common in audio amplifiers. A small voltage applied to the grid of a vacuum tube controls a relatively large current that drives the electromagnet in a speaker, creating movement and thereby sound. Modern solid-state amps are superior in cost, size and reliability, but many people still prefer the warm sound and mesmerizing orange-yellow glow of a tube amp.
Fortunately, there’s a way to combine the distinct sound and look of tubes with the utility of an iPod dock. I’ve seen a few commercial and DIY tube-amp docks, but they’re expensive, uninspired or both. So I’ve come up with a version that anyone can build for about $400.