Microphonic

My son wants to get a tube type amplifier for his stereo. He sent me a link to Maker Shed and Tube Depot, two companies that offer reasonably priced kits. The Tube Depot also offers vacuum tube carrying cases, and they are described:

For maximum performance and longevity, vacuum tubes should always be stored and transported in a safe and secure fashion. The TubeCube and the TubeCube Pro provide a customizable shock-resistant environment for your tubes and helps prevent them from becoming microphonic or damaged.

Okay, "damaged" I understand, but microphonic? What the heck is that? From Wikipedia:

Microphonics describes the phenomenon where certain components in electronic devices transform mechanical vibrations (ringing) into an undesired electrical signal (noise). The term is derived by analogy to older microphones where that behavior is inherent in the design, while with modern electronics it is sometimes an intentionally added effect.
When electronic equipment was built using vacuum tubes, microphonics used to be a very serious design problem. The charged elements in the vacuum tubes would vibrate and the motion would change the distance between the elements, producing charge flows in and out of the tube in a manner identical to a capacitor microphone. A system sufficiently susceptible to microphonics could experience feedback.

Sometimes this technical stuff just comes out of left field and whacks you upside the head. It's perfectly obvious now how vibration could cause problems for vacuum tubes, but it's something I never heard of before. Weird.

My son isn't the only one with the vacuum tube bug. Witness this new car radio, now with a vacuum tube. Update: it's not new, it dates from at least 2005.

And no discussion of vacuum tubes is complete without this video from Claude Paillard:

Fabrication d'une lampe triode
by F2FO

Update January 2017 replaced missing image.