Rolled some 12ax7's recently...

Hi Rodman,
They came with my Dynaco pre-amp. I bought it and a Stereo 70 from the son of an engineer who made it while he was in college in 1965. I don't believe he ever changed the tubes. The tubes test very well in my tube tester.

The tubes have the diamond in the glass inside the semi-circle of pins. There are number codes inside the diamonds (date codes I guess).

I have long since rubbed off the lettering while cleaning the tubes with isopropanol. But the diamonds are of course there as they are molded in the glass.

I know none of you will believe this (until you try it!) but the best way to clean tubes, and especially European tubes with that delicate white printing, is naphtha (as in: Ronsonal lighter fluid.) Anything with even a hint of water in it (almost all alcohols, Win dex, etc) will dissolve the white paint, but not naphtha.

Now you tell me! After I washed off those cool little bugle boys off my Bugle Boys! Should I just toss them and buy some of those more robust Bugle Boys where the bugle boy doesn't wash off?

Thanks for the information! I will give it a try.

B-man I've heard rumors (un-verified by me, mind you) that the BB's with the permanent labels (not the Amperex orange globes) might be fakes. I would suggest doing a bit of research first. I could be wrong of course, however I find "Trust but Verify" to be an excellent approach (in many areas of life actually!)

BTW, according to my techie friend Stephen Sank, any of the minitriodes that say Herleen Holland are out of the same Amperex factory? Just different labels/brands.
.

Thanks Nsgarch for watching out for me. I should have put a "just kidding" type statement after my first paragraph above. Sorry, my sense of humor can be pretty bad or twisted.

I have read articles on the Internet in my research about the counterfeits of the highly valued "NOS" tubes, and one of the first things they mention to look out for is labels that are tenacious and don't wash off.

Actually, as an aside, the counterfeits make me wonder about re-issues. Are they really built to spec of the original tubes, and with the same quality of workmanship? The burning question is, do they sound as good? Anyone have experience with them in comparison to the originals?

From the very first moment that I started cleaning my NOS tubes, I noticed how easily the labels came off. The labels were practically rubbing off in my latex-gloved fingers. And with isopropanol, they came off immediately (the labels, not my fingers). I immediately broke out my tube tester and Sharpie-brand marker, and numbered, tested and cataloged my tubes before cleaning the rest. I matched the tube number to the tube brand and measured specs. I am so happy I did that because now, years later, I can still identify tubes and match them.

Thanks for the tip about Herleen Holland, too. I will look out for them. I like the BB's so much that I am very curious to see if the other Amperex's sound as nice.

Thanks again for watching out for me so that I don't get ripped off -- there are many things I am naive about and it is great when decent people speak up!