A lot of the Tesla equipment is still in use by JJ Electronic in Slovakia who are still making a lot of the popular tube types found in musical instrument amplifiers.

Oh yeah, when they disolved the Tesla tube company their equipment ended up in hands of many people that designed and manufactured audio equipment: back in comunist era it was almost impossible to get decent music/hifi gear so a lot of people went on designing and building their own gear and then went on creating small boutique companies after revolution.

JJ makes the most reliable tubes on the market now. They are fantastic.

I loved when a few years ago one of the motherboard manufacturers brought out a MB with a tube based audio stage.

I had to look this up: http://ixbtlabs.com/articles2/aopentube/

Didn't JJ tubes buy the old Tesla tube factories? I have a bunch of JJ tubes for my guitar amps!

Tesla used to make many millions of tubes per year. There must be many companies that bought their machines + many more still collect dust somewhere. Even that nixie tubes guy mentioned buying tons of equipment and reselling those.

That's cool history to know. Seems a lot of this trade knowledge has been lost

similarly, there's this place https://www.youtube.com/watch?v=KwK8KSAJrGs