The Reference 6SN7 Thread

[MDR30]

Got this Sears/Silvertone 6SN7GTB manufactured by Sylvania. Would be interesting to know which year it was made but I haven't been able to decipher "BNC". Any ideas?

 

[mordy]

Got this Sears/Silvertone 6SN7GTB manufactured by Sylvania. Would be interesting to know which year it was made but I haven't been able to decipher "BNC". Any ideas?

First look carefully under the tube designation 6SN7GTB - many times there is a three digit manufacturing date code there.

The BNC code could be a shipping date code. The following is a guess:
B is the year = 2, most likely 1962
N is the month. Using the alphabet (and skipping I because it looks like 1) the 12 months are sequenced A-M, and then staring the next 12 months again on N = January.
C may be a factory code.
BNC = January 1962

 

[MDR30]

No number. I have a virtually identical tube (marked Philco!), they are a perfectly matched pair, which has the code "17B" on the top. I think that one is from 1957.

 

[Doug2507]

312 is Sylvania EIA, BNC is batch code.

I7B is the manufacturing code, 312 is Sylvania EIA, 5747 is the 47th week of 1957.

 

[MDR30]

Made a mistake in my previous post. The Philco/Sylvania 6SN7GTB code should be I7B (which Doug2507 correctly stated). First letter month, second digit year, third letter factory. So: September 1957, Brookville, PA.

 

[Doug2507]

Made a mistake in my previous post. The Philco/Sylvania 6SN7GTB code should be I7B (which Doug2507 correctly stated). First letter month, second digit year, third letter factory. So: September 1957, Brookville, PA.

Nice. Where did you get the plant info / list of plants?

 

[MDR30]

https://vacuumtubearchive.com/volume-21-number-6/

Page 86, the article "Deciphering Sylvania Date Codes 1943-1988".

 

[Designsfx]

Here are some files for deciphering Sylvania- the page showing the changes in the fonts used can clear up a lot of confusion.

 

[Doug2507]

https://vacuumtubearchive.com/volume-21-number-6/

Page 86, the article "Deciphering Sylvania Date Codes 1943-1988".

Haha, that's my reference but I didn't turn the page to p86.

 

[mordy]

No number. I have a virtually identical tube (marked Philco!), they are a perfectly matched pair, which has the code "17B" on the top. I think that one is from 1957.

Now look at the top of the Philco tube under the tube designation - I can't see clearly but I think it says 84I. This second code is found on many Sylvania tubes under the tube designation, either on the side of the glass under the tube designation, or, in this case, on top of the tube. The second date in this case is a shipping date - April 1958. (I guess the I is a Philco factory designation.)

 

[MDR30]

Sorry, there is no code "under" the tube designation, only below: I7B, September 1957, Brookville, PA.

As for my original inquiry, it seems still to be somewhat of an enigma: the code BNC on the Silvertone 6SN7GTB. I can't remember if Sylvania used this three letter code on their other tubes, seems either to be digits or a combination of letters and digits, but maybe someone can shed a light on this.

 

[TLO]

Sorry, there is no code "under" the tube designation, only below: I7B, September 1957, Brookville, PA.

I7B...that is the code @mordy is talking about.

 

[Jarlaxe]

I know some of you have great experience with Brimmar CV1988 (planning to use it with WE on Envy with Immanis) but i don't know if these are the genuine articles and what are the differences between these two :

https://www.vintage-electronics.co.uk/product/cv1988-6sn7gty-brimar-valve-tube-brown-base-nos-p81/

https://www.vintage-electronics.co....brimar-valve-tube-black-base-black-glass-nos/

I also found these but they are ridiculously overpriced compared to the other two :

https://www.ebay.com/itm/3141864718...HX32AC&hash=item4926f9198e:g:FQkAAOSwCL9jR-rA

Any help is appreciated ! Thanks guys !

 

[Doug2507]

I know some of you have great experience with Brimmar CV1988 (planning to use it with WE on Envy with Immanis) but i don't know if these are the genuine articles and what are the differences between these two :

https://www.vintage-electronics.co.uk/product/cv1988-6sn7gty-brimar-valve-tube-brown-base-nos-p81/

https://www.vintage-electronics.co....brimar-valve-tube-black-base-black-glass-nos/

I also found these but they are ridiculously overpriced compared to the other two :

https://www.ebay.com/itm/3141864718...HX32AC&hash=item4926f9198e:g:FQkAAOSwCL9jR-rA

Any help is appreciated ! Thanks guys !

All genuine. Clear glass are the earliest from these, black base I think are Mullard production (code on top of the glass) and last pair are late 60's Brimar.

Langrex has 3 foil getter black plate Brimars in stock which are the first cv1988 construction albeit they don't have the cv1988 print on them. (they've got a single with cv1988 print / box, but it's twice the price)

I highly recommend getting a pair of these, to my ears they're the pick of the bunch from all the different construction over the years. More refined sounding and a touch of extra body.

 

[JTbbb]

I know some of you have great experience with Brimmar CV1988 (planning to use it with WE on Envy with Immanis) but i don't know if these are the genuine articles and what are the differences between these two :

https://www.vintage-electronics.co.uk/product/cv1988-6sn7gty-brimar-valve-tube-brown-base-nos-p81/

https://www.vintage-electronics.co....brimar-valve-tube-black-base-black-glass-nos/

I also found these but they are ridiculously overpriced compared to the other two :

https://www.ebay.com/itm/3141864718...HX32AC&hash=item4926f9198e:g:FQkAAOSwCL9jR-rA

Any help is appreciated ! Thanks guys !

Vintage Electronics are Stella. They will match a pair for you. I personally like the clear glass brown base.