what tube is it??

[jtmjtm45]

I have a dozen preamp tubes but most or all writing is gone is there any way to tell what type of tube it is .or should i just go by how they test on my tube tester

[Groundpath]

The only way I know is to look inside and see what pin hooks to what component inside the tube. Then compare this to tube data.

[dotfret]

If you can see Philips-style factory codes on them, you have a chance - see the post
http://www.18watt.com/modules.php?name= ... ic&t=13255
these codes were applied to Philips licensed designs, so you have a chance with some makers, but not with others.