I want those! Beautiful. Thank you for sharing. Do they sound any better than the two in your first photo?

I agree. I bought the three GTAs for a pair of AtmaSphere M60’s, they run one of the 6SN7’s at Those bottom two tubes are from the 40’s. They are GT’s. I bought the three GTAs for a pair of AtmaSphere M60 amps. They run one of the 6SN7’s harder than GTs can handle. I agree, lovely tubes:)

AWV Radiotron The pair with the support rods are very special.

maybe a 40’s era RCA 5u4g with a brown base? That tube looks identical to to my RCA 5u4g.

Later versions of the RCA only have one getter. But they are usually a rectangular getter, that dimple foil getter is what is throwing me off.

You could try Westinghouse GTB’s, they are found fairly cheap and sound very good. Raytheon GTB sound decent too and again reasonably priced. I’ve also had good luck buying Australian made tubes from Australian fleabay sellers. Great sounding tubes again at real world prices.

Looks like an RCA 5R4GY to me

My guess is the three Russian made tubes probably have identical construction, so save your money on labeling, it probably won’t make a difference.

It looks to me like the tube in the middle with the black glass is a TungSol tube. Nice sounding tubes.

I agree with you, those older AWV 6SN7’s are fantastic. Some of the quietest tubes I own in the 6SN7 family.

I think so. I go by the internal structures. Look for a 5u4g with the two supporting rods between the plates.

Which RCA are you running? The older ones typically sound a little better.

Believe it or not I have one black glass NU 6SN7 that has the same round plate structure as the 6F8G. I’m sure they are uncommon but they do exist.

I find this post very interesting. I’ve been in the same position as you. I put the 6F8G NU in my preamp and I go, ahhh, that’s nice. A few days later they are back on the shelf. I forced myself to start using my lesser testing NU black glass tubes in one of my push pull amps, I’m glad I...

I have a 5U4G that sounds very refined, a few 6SN7 that are incredibly quiet, and a 12AX7 that I’m still trying to wrap my head around. A lot of times they are labeled Radiotron.

Has anyone tried the Australian made AWV 12AU7? Last thing I need are more 12AU7 tubes but I’ve been impressed with the other AWV tubes I have.

Hello, are these the pads that fit the grado SR325e? Thanks!

Etching on the glass is far more accurate as far as dates, if they even did so. I have Sylvania tubes etched in glass saying late 40’s and the base is stamped something completely different.

29th week of 1955, that’s most likely. Or they made them years prior and then put a base on them and stamped what you see.

Lots of suggestions, but if you have 6F8G adapters the Raytheon T plate version are just that for me.

Music sounds better in the dark anyway

Yes they are earlier than the black glass. The structure is slightly different from what I can see. They have U shaped shields on top of the mica where the black do not. The Sonics are different as well. Nice looking pair you have there.

I hear ya. You have to buy a lot of tubes to find that magically quiet one or two or three or four or five hundred tubes later.

Nice! I use the old American made tungsol. Black glass is one of the first 12AU7 they made back in the early 1950’s I believe. If you’re ever looking they can still be found online for $50 or so. I’d be happy to send you an old TungSol 12AU7 clear glass , you can listen and give me your...