Question about BC21 6sn7 tubes


I was wondering if someone out there could direct me to a reference that would explain to me the differences between the various 6sn7 tubes. I just bought a BC21 and am new to tubes. Is a 6sn7 the same as a 6sn7w, 6sn7gta, 6sn7gtb, vt-231?

I did a search in the forums and found some bc21 owner's favorite 6sn7 tubes from which I can kind of deduce substitutions but thought maybe there was a more definitive list somewhere.

Many thanks in advance.
tooter
Nutella's link is my favorite...

Owning a BC21 myself for many years (and currently in my secondary system) my favorites are...not in any order...

Tung-Sol VT-231
Ken-Rad VT-231
Sylvania 6sn7W (short bottle).

Dennis Boyle's descriptions on that website are very accurate to my ears...
Hi Tooter,

I've owned a BC21 myself for 2 1/2 years and have enjoyed greatly. Along the way I've bought bunch of different NOS 6SN7s such as the Sylvania, Ken-Rad, Raytheon and RCA VT-231s, and other variants of 6SN7s like Tung-Sol and GTs and GTBs.

Although I still haven't gotten around to trying them all, I do have some favorites. The ones that are currently in my BC21 are the black glass variant of the Ken-Rad VT-231. As many people have noted they create a very large soundfield, have great dynamics, great bass and are more organic than the Sylvania VT-231s.

The Sylvanias offer a bit more top end extension and slightly more air. Which one you end up liking will depend on your taste and associated equipment, I just seem to gravitate towards the WWII military versions.

Although I'm not aware of any definitive 6SN7 listing, the links Albert supplied will help a lot, and you can always look up Andy at www.vintagetubeservices.com. Look under octal tubes and you'll find a pretty comprehensive list along with production years and tonal characteristics.

Good luck!