[r one]

And for those who have compared both : internal structure of a 6SN7 Rp and a 6F8G Rp seems to be exactly identical. Both have same plates and same micas. Have you heard a difference between them ?

 

[whirlwind]

  And for those who have compared both : internal structure of a 6SN7 Rp and a 6F8G Rp seems to be exactly identical. Both have same plates and same micas. Have you heard a difference between them ?

I have both, they sound pretty darn close to the same to me...any difference would be pretty minimal IMO
 
Mine is a 12SN7 and not a 6SN7, but that should not matter.

 

[Skylab]

And for those who have compared both : internal structure of a 6SN7 Rp and a 6F8G Rp seems to be exactly identical. Both have same plates and same micas. Have you heard a difference between them ?

I personally found the two to sound almost identical as well. If anything, I slightly preferred the 6F8G Rp. Both super excellent.

 

[gibosi]

  i  thought the same thing but this is for the most older version of Ts Rp which have a circum mica instead of an oval.  in my mind this model was replaced by the oval mica version during the 1940's.
 

 
Actually, it is "SC 645 A". This is the US Army Signal Corps number. Frankly, I do not know the meaning of the middle part but suspect that it is nothing more than an inventory number. For example, here is a 12 volt Tung Sol RPBG with the number "SC 66 A". Unfortunately, it appears that most, if not all, of these 1940's JAN-CTL Tung Sols do not have date codes.
 
However, I have a couple Tung-Sol RPBG, oval top mica spacer, rebranded as Emerson. Both are dated 823 -- 1948, week 23.
 

 
Edit: Also, there is a JAN-CTL Tung-Sol with the same flat-black plates as are often found in Tung Sol 6F8G. Interestingly, to my ears, it sounds essentially the same as the round-plate versions.
 

 

[gibosi]

Has anyone tried the British Tungram 6SN7 (Shown here next to an RCA 6SN7, for comparison)?
 

 
 

 
 
The "KB/T" tells us that this was manufactured by British Tungsram in their Tottenham factory. And "HF" tells us it was manufactured in June, 1952. Interestingly, European Philips acquired the British Tungsram facility in 1952 and evidently kept it going until about 1956. There appear to be production codes on the bottom of the base, but they don't seem to conform to either Philips or Hungarian Tungsram codes and have no idea how to interpret them.
 
Is it N80? or, 08N? or something different?
 

 

 
Anyway, haven't spend much time with it, but it sounds pretty good.

 

[punit]

  Has anyone tried the British Tungram 6SN7 (Shown here next to an RCA 6SN7, for comparison)?
 

 
 

Looks similar to Brimar CV 1988

 

[Oskari]

It's been quite a while but I really liked the Br. Tungsram tube. Lovely in a not-in-your-face way. Don't know about the code.

 

[gibosi]

The Brimar and Tungsram CV1988 do look somewhat the same. However, the Brimar typically has black glass, whereas, the Tungsram has grey glass. And the internal construction, most noticeably, the plates and mica spacers are different.
 
And further, the sound is different. When I think of Brimar, I think lush and bassy, whereas, my first impression of the Tungram is that it is a good bit leaner and more delicate, closer to the B65 than the Brimar. But again, I have had only about one hour with this tube, so you should take my words with several grains of salt....

 

[r one]

very interesting Gibosi about this secret tube code.
 
I have other bgrp military tube


we can read the same kind of code SC 66 A


same code is on the original box but...


on the front, it's indicate december 1944. So there's no link between date and code apparently.
and on this civilian bgrp labelled for Hytron


the code is different and unreadable

 

[whirlwind]

  Has anyone tried the British Tungram 6SN7 (Shown here next to an RCA 6SN7, for comparison)?
 

 
 

 
 
The "KB/T" tells us that this was manufactured by British Tungsram in their Tottenham factory. And "HF" tells us it was manufactured in June, 1952. Interestingly, European Philips acquired the British Tungsram facility in 1952 and evidently kept it going until about 1956. There appear to be production codes on the bottom of the base, but they don't seem to conform to either Philips or Hungarian Tungsram codes and have no idea how to interpret them.
 
Is it N80? or, 08N? or something different?
 

 

 
Anyway, haven't spend much time with it, but it sounds pretty good.

I have not tried it ....but now I want too.

 

[larcenasb]

The prices for Tung-Sol RPs are depressing. Finally, I bought a low testing Tung-Sol RP for cheap just to finally hear it and hopefully conclude it's not for me ...sigh, it sounds perfect in my system.
 
AudioQuest DragonFly v1.0 --> Bottlehead Crack --> AKG K240 Sextett

 

[ericr]

i  thought the same thing but this is for the most older version of Ts Rp which have a circum mica instead of an oval.  in my mind this model was replaced by the oval mica version during the 1940's.

A while back I tracked one of these "codes in white box" imprints (from a Raytheon 6SN7W IIRC) to the website for/honoring members of a specific WWII Army Signal Corp regiment. It was an interesting read and various artifacts shown used the same imprint, but it was pretty clear to me it had no value in identifying the tube itself (outside of a WWII era manufacturing date).

-Eric

 

[jamato8]

  The prices for Tung-Sol RPs are depressing. Finally, I bought a low testing Tung-Sol RP for cheap just to finally hear it and hopefully conclude it's not for me ...sigh, it sounds perfect in my system.
 
AudioQuest DragonFly v1.0 --> Bottlehead Crack --> AKG K240 Sextett

Even the boxes of some of the USN TS RP were beautiful. I have a pair of NOS and the box is a thick cardboard with heavy print in a nice blue wide print. The boxes are like new and don't break down like some older cardboard so I assume they are even acid free. I have a few sets of RP and they are nice. Too bad they got so expensive but they are getting harder to find. I think I paid 5 dollars each for my NOS, but that was a few years ago. 

 

[r one]

Wow 5 dollars !! 5 years ago ? 10 years ?

 

[jamato8]

Wow 5 dollars !! 5 years ago ? 10 years ?

This was around 11 years ago, maybe a little longer. A place was going out of business. They had a number of tubes and more of these. When I got them I called them but they had sold the rest.