Today, at a sale, I found 5 12ax7 tubes which say "Made in Germany" and also have the brand name "CEI" on them. Does anyone know anything about these tubes (who made them, etc.) There is no Telefunken "diamond" logo on the bottom and I wonder if they would have been made by Siemens. Thanks.

Pics?

I found this,http://www.hifiwigwam.com/showthread.php?24587-CEI-Tubes-Says-made-in-England.

Is there an EIA code? That should tell you how they sound.
Actually, it would let you know who made them.

I have yet to witness a tube "sound" like anything to anyone who was not coached to "hear" it in advance....



Larry

Nonsense galore! I'll tell you this, the Telefunken 12AX7 tubes of yore are very unlikely to be microphonic, likely to have matched emissions if it matters in the application, and are extremely hardy and dependable. It would be easy today to reproduce these classics provided there was a rational business reason to do so. Alas it is not the case.

+1

L

Look at the top of the tubes.If the glass has
seams in it that look like a cross then it is
probably made by siemens or valvo.Look for
the acid etched codes near the bottom of the base.
There are web sites you can go to that have charts
to decode the numbers and symbols to find out
who the manufacturer is.We really need
to see some pictures to give you a definite answer
as to who made it.It could also be a falsely branded
eastern European tube.
Regards,
Swanson

"likely to have matched emissions if it matters in the application" -
I fail to see how the tube manufacturer could know what applications would apply to so generic a tube. I'm not meaning to poke. I'm just observing. As for tubes with specific applications by design; I expect that, just like with ASICs today, those customers typically could (and did) pay for just about whatever they wanted. Telefunken's reliability is not in question as far as my opinion goes. Their prices today does seem to be out of line, but, whatever sells - sells.

Back to the original question: The OP wanted to know manufacturer and the EIA codes should tell better than anything else.

I probably should (and will) be chastised for making any reference to "sound - vs- brand." I rather derailed the thread. For that , I apologize. My fingers think faster than my thinker, sometimes. Well, out of sync, anyway.

The EIA code probably will not help. The supplier was allowed to provide their own code, so it does not have to be the code of the actual maker (eg the "922" code on International Servicemaster tubes, although International made nothing). Also, most foreign tubes do not have an EIA code on them from the factory.

CEI was a rebrander and rebranded and resold tubes made by anyone.

The only ways to positively identify decent tubes made in Germany....

Telefunken made in Germany will have the diamond impressed in the bottom of the glass as well as a pretty identifiable plate structure.

Seimens will usually have a Philips-type factory code that looks like a "does not equal" sign.

Valvo-made will have a "D" factory code.

If really German, they are most likely to be RFT.

Jim Cross

More German factory codes Philips style:

Telefunken capital font ¨T¨ upside down
Tungsram capital font ¨L¨ upside down
Loewe Opta code: II

Jard N.