[mrwinick]

I have four tubes (three black glass, one clear glass) and they all have differently shaped mica. Even the two round plate tubes that I have. Any significance to the different mica shapes?

 

[Skylab]

At least that I can tell, the mica shapes don't matter. I have one clear class has the flat black plates - I have then 4 of the black glass-round plate ones, and they do have 2 different types of Mica - my VT-99 labeled ones have the essentially oval mica that is identical of the super-expensive T-S BGRP 6SN7GT. My "non-military" BGRP 6F8G's have a square/diamond mica. But I cannot tell any difference in the sound between the two.

 

[Black Stuart]

Interesting comments from Skylab. I have a good stash of 1578(6SN7) Russian specials.
The internals come in 3 different styles and there is just a very slight difference, which are discernable via a head amp but not through speakers.

 

[Skylab]

I should clarify - there IS a difference between the flat-plate clear-glass Tung Sol and the round-plate black-glass ones - just no difference between the different-mica versions of the BGRP ones.

 

[blubliss]

mrwinick, do you mind telling us where you got the tubes. I am looking for some myself. I have a round plate and a square plate, but I would like another round plate.

skylab, can I use the ones with different plates together in an SDS-XLR?

Thanks for any help.

 

[Skylab]

Quote:

Originally Posted by blubliss /img/forum/go_quote.gif skylab, can I use the ones with different plates together in an SDS-XLR? Thanks for any help.

Sure, in that it will function OK, but it might not provide the best possible results.

 

[mrwinick]

Quote:

Originally Posted by blubliss /img/forum/go_quote.gif mrwinick, do you mind telling us where you got the tubes. I am looking for some myself. I have a round plate and a square plate, but I would like another round plate. skylab, can I use the ones with different plates together in an SDS-XLR? Thanks for any help.

Absolutely.
Mike Marx at 'vacuumtubes.com'
It takes a while for Mike to respond to emails, but the tubes are great. I bought a ken-rad, and 3 tung-sols (one clear glass and two black glass round plate). Enjoy.

If he is out of them let me know I might have another idea of where to go

 

[mrwinick]

I want to mention that I have a black glass, flat plate TS (from a different vendor) so you should specify if you want round plate.

I also just looked at my sylvania (that I like a lot) and it is also round plate. On the other hand, the Ken-rad (that I also like a lot) has a flat plate.

I'm starting to have a lot of fun with tubes.......

 

[blubliss]

Thank you both very much.

 

[mrwinick]

I did a search on another site and found some info.
>>
Posted by Len_ (A ) on September 17, 2006 at 00:40:17
In Reply to: tungsol round plates 6SN7 ? can some one tell me pictures inside posted by lovetube on September 16, 2006 at 23:08:21:

The two tubes you have are both Tung Sol round plates. The tube on the left is the first version, circa 1943. Both top and bottom micas are full round design. The tube on the right is the second and more common version, circa 1944-1945. Both top and bottom micas are oval shaped with metal spacers flaking the sides of the top mica only.
Tung Sol is not the only manufacturer to produce round plate 6SN7s. Neotron of France and National Union's black glass are both round plate structures. Neotron's design is similiar to Tung Sols, while NU's, while round in circumference, is very different. <<

 

[Frihed89]

Skylab pushed me in the direction of the round plates, and i have never been happier. I have these as an input to both my deHavilland UV2 and SP MPX3 Slam SE

 

[blubliss]

mrwinick, no luck at vacuumtubes.com.

Anyone else have a source for them they are willing to share?

 

[Skylab]

Look for EBay seller Beunos Aires Radio and ask him. That's where I got mine.

But the secret seems to be out - these have been steadily creeping up in price.

 

[Black Stuart]

Buenos_Aires Radio,
as Skylab says is a very good supplier. He packs carefully and the matched 4 x Syls I bought were quite clearly unused NOS.

I also bought 5 x Tung Sol RPs from Hong Kong, used but tested strong. I have a question here - one of the Tung Sol is a little wobbly between glass and base - what glue should I use to make this secure.

So who bought the 2 x National Union tubes which sold last night on Ebay/US. I was tempted but refrained.

 

[Skylab]

I wouldn't try to glue the base. Very few glues will withstand the heat. A loos base isn't a big deal as long as the tube has no other problems (leaks or shorts).