Identify tube

How does one identify tubes? There are no markings on a set I have.
Normally I would go to a website like or and do a visual comparison of the tubes I have vs. what they show.

Were the tubes you have from a tube power amp or a tube preamp?

Sometimes I've just taken pictures of the tubes and sent them to Brent Jessee or Jim McShane along with some physical measurements of them and they helped me identify them.
This can be risky. Even if you know it was an audio tube, the missing letters, (e.g.,B,C,GT) can leave you with a tube rated for 350 plate volts, when your amp requires one that may run around 450 plate volts. There is no sure way of knowing this without those letters.
I'm pulling them from my amp so I know they are EL34s, would there be ones with different voltages for these?
There were some modern ones from Russia, or Tesla branded tubes that could handle a little more voltage. In general, I think if they are an EL34, they should be OK for anything calling for them. If your wanting to see who made them, a good tube dealer may be able to help you identify them. Good pictures can help too. The 6L6, and some other number tubes needed the letters also. Could be a Mullard, Amperex, or another European, UK, and even US tubes, if they are old stock. I was under the impression you didn't have any numbers, and just ran across them somewhere. Some TV tubes look like they were make on the same equipment, with the same parts, but were totally different inside. This should not be that kind of case, with EL34 tubes.