[alvin sawdust]

   
Another option: I usually use fine sandpaper to clean octal pins.

Thanks for this tip. It has brought a MWT 6AS7G back from the dead and stopped a CBS 5692 and Marconi B65 from hissing. I always clean the pins with deoxit but evidently that wasn't enough even though the pins looked fairly clean. 
So all in all some fairly expensive tubes salvaged and my amp has never been so quiet. One happy bunny here 

 

[mordy]

Hi Gibosi,
 
I know that there is information out there how to decode the sand blasted dots on the GE tubes, but I have yet to find out how to decipher the codes on some Tung Sol tubes using letter combinations.
 
Here is an example from a 6BL7GTA tube that says:
 
322PP-E.
 
Do you have any idea what PP-E stands for?

 

[100VoltTube]

Tung-Sol used a lot of dating systems that we know nothing about. I have a 14F7 that appears to have the year on the octagon around "14F7" on the top of the tube and and the week, "22" printed right after "TUNG-SOL" Unless the "22" is part of a 3 digit code and the last digit has come off. Of course, it was made by Sylvania, so the date code might not actually refer to the date it was made.

 

[teamrushpntball]

Hmm, my tube doesn't seem to have any markings like that.  Trying to find anything about it I can.  Is it a real Tung Sol 5998?  Came with an amp so not that upset if it is, and it sounds better than my 6080 and 6as7g Chathams.

Spoiler: Pictures

 

 

 

 

 

[gibosi]

These weird date codes were used by Tung-Sol and others on consumer grade tubes, that is, tubes commonly used in televisions and other home electronics. Some speculate that consumers were checking the dates on tubes and bringing them back to the dealer because they were a year or two old. They wanted "new" tubes. lol
 
So the manufacturers starting using dating systems that could not be deciphered by consumers. And unfortunately, I have yet to find the key to enable the reading of Tung-Sol date codes...
 
As for the 5998, 6080 and other "industrial" tubes, since these were not commonly used in consumer electronics, but rather, in industrial, commercial and military applications, standard military date codes were used.

 

[gibosi]

  Hmm, my tube doesn't seem to have any markings like that.  Trying to find anything about it I can.  Is it a real Tung Sol 5998?  Came with an amp so not that upset if it is, and it sounds better than my 6080 and 6as7g Chathams.

Spoiler: Pictures

 

 

 
This was manufactured in 1959, week 33. It is a real Tung-Sol manufactured in the original Chatham factory, which was acquired by TS in the mid-1950s.

 

[mordy]

Don't forget that some 5998 tubes were made for early computers, and may say IBM on them.

 

[432789]

tube hoarders please start selling if you have more than you need.

 

[attmci]

  tube hoarders please start selling if you have more than you need.

There are tons of 6bl7s on the market now. 

 

[432789]

There are tons of 6bl7s on the market now. 

C

Woah! I just din't know, which make should I look out for? Thanks man

 

[attmci]

C

Woah! I just din't know, which make should I look out for? Thanks man

http://www.head-fi.org/t/806043/for-6bl7-tube-users/480#post_13334889

 

[abvolt]

 
Quote:

C

Woah! I just din't know, which make should I look out for? Thanks man

I like both plates the one I'm currently using are sylvania flat ribbed plates very nice sq..

 

[gibosi]

  http://www.head-fi.org/t/806043/for-6bl7-tube-users/480#post_13334889

 
That quote of mine is in regard to 6BX7, which I primarily listen to. So I really can't say much at all about the sound of 6BL7.
 
That said, given that both the 6BL7 and 6BX7 are quite cheap, I would encourage you to try several brands. GE and Syvania are the most plentiful. And during the early to mid 1950's, it appears that they were the only American manufacturers. Tung Sol and RCA didn't begin manufacturing these tubes until the late 1950's, so before that, they sourced these tubes form GE and Syvania and simply put their name of them. And Toshiba and NEC manufactured these tubes as well.
 
Again they are cheap so buy lots of them and have fun! lol
 
Edit: And as this is the 6AS7 thread, if you want to try these tubes, I would encourage you move to the 6BL7 thread:
 
http://www.head-fi.org/t/806043/for-6bl7-tube-users

 

[432789]

I tried to buy 2 into 1 adapter for my darkvoice amp from eBay Hong Kong the seller let me know that it won't work, this are his words "because darkvoice amp different design Elise amp.darkvoice amp one channel using half 6AS7 tube,but Elise amp one channel using one tube,if insert adapter and tube,amp have hum noise." Does anyone have experience with darkvoice? Thanks

 

[attmci]

I tried to buy 2 into 1 adapter for my darkvoice amp from eBay Hong Kong the seller let me know that it won't work, this are his words "because darkvoice amp different design Elise amp.darkvoice amp one channel using half 6AS7 tube,but Elise amp one channel using one tube,if insert adapter and tube,amp have hum noise." Does anyone have experience with darkvoice? Thanks

You may want to post your question to the darkvoice amp forums too.