With some types, yes. There are a number of videos and articles 'out there' I have tripped across over the years though I have no links for them. Sometimes they use 'standard' types, but also those designed specifically to run with a 12V anode/plate voltage for use in cars. Most of these are of the 'space charge' type where the G1 is deliberately used with a
positive bias voltage. They are a specialist area of tube use and because of that there's plenty of NOS (New Old Stock) versions available real cheap as no-one wants them.
In a similar vein "Compactron" tubes are cheap and plentiful. Try here...
http://www.junkbox.com/electronics/Comp ... ndex.shtmlThe tubes and bases still available, again cheaply for the same reason, and worth thinking about.
As for using standard tubes at low volts, it can be done, but the results don't really deliver, not really worth the effort in my opinion...a novelty...if it were any good manufacturers would have used the concept to make their products cheaper, they didn't.
To use conventional tubes in a car radio the 'vibrator power supply' was developed. I remember these from the 60s (just). When you turned the radio on you heard a low buzz or hum before the tubes warmed up and delivered sound.
https://www.radioremembered.org/vpwrsup.htmSteve A.
I just noticed the 'junkbox' link I added is very similar to the first one Harry listed...