[Xcalibur255]

Was there ever any consensus on whether the 2399 is electrically a 5998 or a 6AS7?  I've read through this entire thread but it seems like no certainly was established.  I ordered a pair of 5998 from a tube seller and what I received were Chatham 2399.  They have 5998 plates, but if they are electrically a 6AS7G then that would basically make them a 6520 which isn't what I was looking for.  They also have copper grid posts, where as my understanding is the 5998 usually uses steel.  I'll probably keep them regardless but I'm hoping I can figure out whether I can put them on the 5998 or 6AS7 side of my tube box. 
 
There are some nice looking 6520 on eBay I'm considering bidding on right now, but if the Chatham 2399 is the same tube then I will pass on that.  If, however, they are a 5998 then I'd still be bidding so I'm hoping to find out.  Thanks guys!

 

[Skylab]

I'm not sure we will ever really know. I've searched the web over many times, and never found a 2399 data sheet. I have seen some folks say it's a 5998, but if that were true, why the different number designation? Especially since only Tung-Sol ever made either one?

It's also funny that I have Tung-Sol 6520 tubes which look like 5998's internally, and others that look like 6AS7G's. Odd.

 

[Xcalibur255]

Hmmm.  Maybe they are a little bit of both, but my thought was if they are electrically a 5998 that would be confirmable by using them with a high power ortho and seeing how much drive they have compared to a 6AS7.  I've read from quite a few users that the 5998 really excels with power hungry headphones.  At any rate I'm kind of glad I have them since they are somewhat unique.  Thanks for your input Skylab, if you don't know then the info must be very obscure indeed.

 

[Skylab]

There is no doubt that the 2399 is a good sounding tube! That much at least we do know

 

[Xcalibur255]

The more I examine the 2399 the more little details keep popping out at me.  There really are a number of differences.  Most easily appreciated is the presence of a 3rd spacer tab holding the top mica against the glass, probably to improve on microphonics.  There is an additional coating of some kind on the plates that was sprayed on after the micas were fixed in place, because you can see where the overspray, blocked by the plates, forms a cross on the bottom of the mica.  There is also an additional coating or jacket on many wires which are normally bare in the 5998 and 6AS7G.  Most obvious would be the copper grid posts and grid wires in place of the normal steel ones.  It looks like the pins have been tinned for some reason as well, which made cleaning them far more aggravating because of the rough texture.  I'm guessing it was done to make them more resistant to oxidation, but the parts that have blackened stubbornly insist on staying that way no matter how much I work at them so hopefully it will not present any noise issues with electrical contact.
 
Overall a very neat tube.  There is an alarming amount of loose broken glass inside one of them, which I know is no big deal, but it is still strange to hear it sound like a cheap broken chirstmas tree ornament whenever I move the tube. 

 

[Ultrainferno]

So what's the story of (RCA) 6AS7G heavy plate tubes? They're not grey and not black, but how do they sound?

 

[john57]

Has anyone tried the Shuguang 6N5P (6AS7) tubes and how they sound?

 

[Skylab]

They sound awful.  If you want cheap, the Russian version is much better.

 

[john57]

.

 

[librarian]

Subscribed!

 

[Capt. Z]

Subscribed

 

[john57]

I have not see this kind of 6N5S or 6F5M? tube shortly tube before

  Is this tube even compatible to the 6AS7 tube?
 

 

[Skylab]

Not compatible in any way, shape, or form.

 

[john57]

It was for sale at eBay http://www.ebay.com/itm/6N5S-6AS7G-ECC230-tubes-NOS-5ps-Vintage-Soviet-/140709499805?pt=Vintage_Electronics_R2&hash=item20c2f0939d I think that the seller just mess up with another listing. I was thinking about a different version of 6F8G but it is not.

 

[Skylab]

Just proving you cannot use eBay ads as a tube substitution guide. Wrong base, has grid cap, and looks like a single triode whereas the 6AS7 is a dual triode. The only good news is that because the base is different, I don't think you'd be able to actually plug one in and watch your amp exPlode.

That tube has a gain of 100, and the 6AS7 has a gain of 2

EDIT: in looking again that might be an octal base. So I take it back...one might very well be able to damage their amp permanently by trying to use those tubes in place of a 6AS7...not to mention what would happen if they god forbid touched an uncovered grid cap with the amp powered up...scary.