Fake AC701. Caution

[SparkleBear]

Hey all,

Not sure where else to post this. Fake ac701 on eBay and reverb right now. Just don't want anyone to fall for it. Makes me frustrated but alas such is as things are ...

https://m.ebay.com/itm/RARE-VINTAGE-TELEFUNKEN-AC701-TUBE-FOR-NEUMANN-SCHOEPS-MICROPHONES/332439247800

Cheers all!
Eric

 

[Walrus]

How can you tell this is fake??

 

[Telefunken_Elektroakustik]

How can you tell this is fake??

The most obvious issue is that AC701 have only four leads set in the glass bottom, not the seven you see here. However, even if the leads were  correct, to a trained eye that AC701 stamp and especially the red indicator dot appear to be imitations. Even the shape of the glass nipple at the top of the tube could be suspicious, it appears wider and flatter than most AC701.

It's worth noting that this seller may have no clue as to what they are selling and if it is genuine or not.

 

[Walrus]

Ah yes, I see, hadn't looked at the leads only at the label. Not seen enough genuine ones to know if the printing is wrong.
The one I have here is def a genuine one, just isn't an original Neumann one. No red dot.

 

[Pip]

IN MY OPINION. Also experience. There are no AC701K tubes available with the exception of someone who you trust impeccably who is in the NOS tube business and even then they can not vouch for the usability of a tube unless it has been installed in the target circuit and listened to!

From a far more quotable source then I:

http://repforums.prosoundweb.com/index.php?topic=4767.0

 

[Michael Tibes]

https://www.ebay.de/itm/AC701-Telefunken-NOS-tube-rohre-NEU-test-100-NEUMANN-SCHOEPS-ROHREN-Micro/372141977820?hash=item56a563f0dc:g:ctYAAOSwvjdZRUlB

now in Germany as well? It claims that the location was Berlin, local pickup possible.



Blurry pictures, unclear if the bid is for one or both tubes pictured, 'funny language'...

Some maybe more legit pics here: https://tubedepot.com/products/ac701
The price is maybe not soooo legit though...

Michael

 

[ln76d]

Don't have to be a Sherlock to see it's poor fake... Wow...

 

[Zebra_PD]

I won an eBay for one that look like ones in this post with more then 4 leads, only paid 10 USD  knowing its prob a fake. Untested from a private seller in the states. Thought its was worth a long shot, like buying a ticket for the Eurojackpot lottery haha

Will post some photos when I get it.  What made me curious is that the Amperex (Philips) 8254 EC1000 Triode that is stated to be similar to the AC701 also has more then 4 leads. Or is it not even possible for a ac701 ever been produced with more then 4 leads?

Any one with the right knowledge and equipment in the EU (perhaps even Sweden?)  willing to help me out testing it? Don't have a tube tester etc of my own and don't want to stick it in a microphone totally untested in case it blows up or something.

 

[emrr]

4 leads on the bottom, 1 on the top. 5 total. 

https://frank.pocnet.net/sheets/128/a/AC701.pdf

 

[e.oelberg]

well I followed the link and what I saw was a ac761 from neuhaus, which is the east german equivalent to ac701k and electrically interchangable. Not really a fake

 

[rodaffleck]

well I followed the link and what I saw was a ac761 from neuhaus, which is the east german equivalent to ac701k and electrically interchangable. Not really a fake

To avoid confusion: the original e-bay listing was absolutely a fake with the wrong number of leads. It appears as though the auction has been removed, so presumably the seller had been notified that it's not a legit tube. Currently, if you click on the lead now e-bay provides a "more chances to get what you want" category which shows an auction for an AC761. The AC761 in question is a different tube, different seller than what triggered this thread. I assume that this is what e.oelberg is seeing and what prompted the response.

As for the legitimacy of AC761 tubes, at least the seller of the "more chances" auction is being up front with what they have. But Klaus has gone on record advising against using them as an AC701k substitute:

[quote author=Klaus Heyne]
The East German, state-owned, RFT company made a tube like the AC701 that was used in Neumann/Gefell's pencil and stereo tube mics. That tube was called "AC761", and looked almost identical to the AC701 made by Telefunken in Ulm, West-Germany. But this tube, nominally with the same specs as the AC701, was often noisy from the start and those that were not, usually became unreliable in the long run.[/quote]