sylvania authenticity tube question

[seti]

I took me forever to win an auction on some Sylvania 6SN7WGT tubes but a dozen auctions later and they are mine.

The auction says they are "matched pair of strong 1940's Sylvania

Chrome Top, black plate brown base 6SN7WGT's" but they look

more like some 1970's Sylvania 6SL7's that I have. I checked

tubeseller.com but could not find an example like the ones I bought.

Now I still would have bought them for what I paid but was just curious

if anyone knew for sure if they were 40's or not.

Thanks

Seti

[jt1stcav]

My 6SN7s are '50s vintage RCA black plate 6SN7GTBs, with black bases with the writing printed on the base and not the glass like on yours (the famous RCA octagon designator is on the glass, though). I'm assuming that most all octal and larger American tubes of the '40s and '50s era had stensiled lettering on their black, brown, and even chrome bases and not on their glass bottles (minus the European Mullards and Telefunkens, et al). My only Sylvania is a NOS 1951 5U4G with the printed base. Your 6SN7s do remind me of newer '70s and '80s vintage tubes with their lettering printed on the glass instead of their bases, if that's any indication of what decade they were actually built. I'm a tube nube, so this is only a guesstimate!

[DRBILL]

Sylvania 1940's Black Base, short glass, large gettering These are very rare NEW (NOS)/Used

Sylvania 1950's, early 60's Large brown colored base, Large gettering. These do differ quite a bit from the 6SN7W's listed above. They, too, meet milspec ratings for shock and vibration which should result in improved microphonic performance.

The above quotes are from Michael Marx website: www.vacuumtubes.com

Hope this helps.

DRBILL

[mike stehr]

Here's a Chrome-Top 6SN7GTB, the microphonically challenged finicky things that they are.....they do sound nice.....