[mrAdrian]

But is the tube on the ebay link a 5998 or a 6as7?

 

[Xcalibur255]

Because of the history with 6520 tubes, it is difficult to know for sure.  Normally you would be sure it was a 5998 by the plate style if not for this, but the 6520 was known to use both 6AS7 and 5998 style plates.  So your tube could be a 5998 or a 6AS7G electrically.  You've found something rather unique.  I think the most likely explanation is that for whatever reason the tube was made as a 6520 but ended up being branded as a 6AS7, possibly during quality screening.  The 6520 was a premium version of a 6AS7G.
 
The answer should come from listening to the tube.  The 5998 has a different sonic signature from any 6AS7G tube.  It also has higher gain.

 

[rosgr63]

Here is a 50's Tung-Sol 6AS7G Black Plates, Steel Grid Posts
 

 
 
Here is a 60's Tung-Sol 6AS7G Black Plates, Copper Grid Posts
 

 
 
I like the both but the RCA 6AS7G is my reference tube.

 

[mrAdrian]

Hmm then I guess mine is probably a mistake given your pics xp Good thing is no matter if its a Tung sol 6as7g or the 5998, they are both a nice sounding tube, right?
 
Xcalibur you mentioned the 6520, and that it is electrically a 6as7. So I can still use that tube on my DV336 correct?

 

[Xcalibur255]

Yes, you certainly can.  They are quite rare though.
 
@ rosgr:  I do enjoy the RCAs, they have a very lovely warmth that reminds a person why they got into tubes in the first place.  At the end of the day, though, they are too sloppy in the bass and a little veiled sounding for me, as pleasant as they are tonally.  What the Tung Sols bring to the table is transparency and better signal control.

 

[john57]

Quote:

Yes, you certainly can.  They are quite rare though.
 
@ rosgr:  I do enjoy the RCAs, they have a very lovely warmth that reminds a person why they got into tubes in the first place.  At the end of the day, though, they are too sloppy in the bass and a little veiled sounding for me, as pleasant as they are tonally.  What the Tung Sols bring to the table is transparency and better signal control.

I would agree with this statement as it mirrors my experience with the Glenn amp.

 

[williaty]

Is anyone aware of fake/counterfeit GEC 6080WA or 6AS7 tubes? I'm being offered two at a decent price from a seller in Hong Kong but the phrase "decent price" doesn't naturally occur next to "GEC" :lol:

 

[Skylab]

It could be that they are some other tube that has been relabeled. If you can, get a picture and post it here.

 

[williaty]

 

[Skylab]

Those sure look like the real deal to me.

 

[ValentinHogea]

Just wanted to say that there are some rare tubes on sale here...
 
http://www.ebay.com/sch/retailtechforless/m.html?_nkw&_armrs=1&_from&_ipg=25&_trksid=p3984.m1426.l2654&_clu=2&_fcid=192&_localstpos&_stpos&gbr=1
 
Matched pair WE 421A's
Tung Sol/Chatham 5998's
Bendix 6080's
Sylvania 7236's
GEC 6AS7G (several matched brown bases)
 
and more...
 
Want to clear out that I have no affiliation with the seller...
 
Heads up!
 
- V

 

[Silent One]

Thanks for the heads-up! Been lookin' for some those...

 

[ValentinHogea]

I got me a pair of strong 5998 and Sylvania 7236's.
 
Maybe even a pair of 421A. But my wallets has a max, so I hope I don't get outbid.

 

[Skylab]

Everyone remember - the WE 421A is just a rebranded TS 5998.  EXACT same tube.

 

[Xcalibur255]

Aside from slightly higher amplification factor and transconductance.  This is probably why people sometimes think they sound better, because they'll be just a tad louder at the same volume than a 5998.