Hey 6SN7 fans, I noted the other day that Andy, at Vintage Tube Services, has a "new" tube in the lineup. Intriguingly it is shown as a 6SN7-VTS in the Sylvania section of his current stock list and described as: "This is Sylvanias answer to the Tung-Sol round plate 6SN7-GT/VT231. A true round plate ultra high vacuum 1940's tube with adapter. I just discovered these in 2021. Ready to plug in & amaze you." I called him up and had a nice chat with him. He was a little cagey about what the tube actually is but it's a Sylvania with a loctal base that is the same pinout as a 7N7 but it's not a 7N7, it's a 6SN7. Yes, I know a 7N7 is identical to a 6SN7 but for the pin assignment and base, but I'm just repeating what he said. He said he found a stash of them during one of his countryside wandering trips. As for sound, he indicated they sound very much like a Sylvania 6SN7W with a very slightly softer top end most similar to a Tung-Sol round plate. His price includes the adaptor, but if you have adaptors already he will discount them. I ordered a couple to try, but be advised he said they are super busy and running well over a month behind. I don't expect to see anything until the new year. Cheers, Robert
Sylvania 7A4, check here: VinylSavor: Tube of the Month : The 7A4 I know I saw this somewhere before...
Mmm, nice sleuthing work but I don't think that could be it. For one, it's a single triode so you would have to have a 2-tubes to 1-base adaptor. And Andy would definately have mentioned that. Secondly, the pinout is not the same as the 7N7, so the 7N7 adaptor won't work in a socket for a 6SN7, even for the one triode it does have. And Andy said the adaptor was the same as the 7N7. Personally I think the tube IS a 7N7 but perhaps a very early version that was labeled differently or had some oddball number assigned or even mistakenly printed. Anyway, I'm curious to hear what others speculate and also to actually trying one out. Cheers, Robert
You know..I thought I would stop rolling different tubes after 5687/7119 but then I have just ordered a pair of early version of Philips ECC40 to try out It is Covid-19's fault...
In the past Andy's tubes would arrive in about two weeks time. I'm currently at 4 weeks waiting for my tubes to arrive.
Andy was fun to speak with actually. Like anyone in the thick of the hobby he is strongly opinionated, but refreshingly non-aggressive with his thoughts and, frankly, he likely knows more about tubes than just about anyone. Surprisingly he had never heard of Melz tubes or the 1578 at all, yet he was gracious enough to let me ramble on my nonsense about how nice they are and how I fixed a noisy one. He, of course, is well aware of how tubes can lose conductivity in one or more pins and has fixed more than his fair share. Anyway, yeah, he was up front about how far behind they are in filling orders. I'm in no huge hurry anyway. Cheers, Robert
I had tried several 7n7 tubes with adapter but not impressed with them at all. They sound mediocre but not tettibly bad either.
I had a mild interest previously in trying the 7N7 based on some positive comments here at SHF. But the acknowledged go-to place to get genuine NOS tubes is JACMusic in Germany and they never bothered to reply to my order request, both times I tried. These ones from VTS may not be 7N7 - in FACT Andy says they are not. In any case I have some level of trust in his judgement and he says they are a very nice tube, if not necessarily "the best", of which we all know there is no such thing. Worth a try in my mind, at least for me. Cheers, Robert
If you study the plates of most 7N7 closely, you will know why. They are basically angled T-plate, yes, same as Sylvania late 6SN7 GTA and GTB. Ppl who highly recommended them must also like angled T-plate GTA amd GTB. Not my cup of tea.
I haven't seen any 7N7 close enough to be able to see internal construction detail. I do see some 7N7 that appear much older than the ones at JACMusic, ones with metal base and black glass, chrome top Sylvania. Curious to some degree. Interesting you mention the angled T-plates. Some of my favorite, affordable, tubes are the later Sylvania GTA with those angled plates. In fact, I have a few earlier Sylvania GT that are a taller tube with clear glass that are T-plates parallel to each other and when I tried them previously they sounded sub-par. However, given most people seem to think the parallel ones sound better than the angled ones, I tried them again on the weekend. And, yeah, not sure what I was hearing before that made me disregard them, but they sound very nice. Better than the angled ones? I'm not sure, but I'm keeping them in for a little while. Cheers, Robert
I like the GTA angled T-plates, very lively top-end. I have a pair of both types, not sure if I hear a difference. These are GT bottom-getters from late 40's to mid 50's. I replaced a GTA with this as a driver in my amp and I like the refined highs (a Brent Jessee recommendation). Also has more low-end. There are also GT flat staggered plates from the same period which are less dynamic.
I probably shouldn't have, since it's beginning to seem like some weird addiction, but I grabbed a couple early GTA with the parallel plates that people seem to consider to sound better than the angled plate GTA I have, both chrome tops. They were cheap, so no big deal but I'm curious. Yes, I agree these GT clear glass are bottom getters. I'll have to look more closely but I didn't spot any obvious "mirrored" surface creeping up from the base, they seemed entirely clear. And, now that you mention it, I do recall thinking that the bass was quite good for a tube that I had, for some reason, previously thought was really nothing special. Cheers, Robert
I also have Raytheon vt231 with T plate which sounds lively and detailed. Thus we should not discourage people from trying tube with T plate. Tube rolling is like mix and match. You shall coose one which fit your sytem and taste. I enjoy going back and forth between the tubes like wine tasting. You do not want to drink same wine everyday.
Well, the getter has to be somewhere, lol. And these were made during the years of VT-231 tooling, so no top-getters yet.
Update for anyone still paying attention or caring about the thread... Andy of VTS has not yet called back to confirm my order, which is completely as expected since he said it would be in the new year. I think I may well pass on this order for those "mystery" tubes. @tlowe contacted me with another candidate this tube may be and I think he's absolutely correct. We're betting they are 7AF7 loktal base tubes. I don't know why these tubes exist as they are essentially 7N7, very similar specs. But the ones I have since tracked down are all round plates so this combined with Andys comments says bingo to me. Chrome Tops. How do they sound? Meh. They're fine, absolutely without much character. I suppose that is a good thing. Actually, they are slightly dark, much like early RCA grey glass with perhaps a little more on the top end. Neutral but smooth, slightly dark but not veiled. Happy to have a few in my supply, but not my go-to tube for my current gear. Ok, this wouldn't be a Robert post without becoming a novel... So I was fishing in the rabbit hole and pulled out a bunch of 7N7. I know what our OP said about them, but I just have to hear for myself. And, @thomaskong is both correct and incorrect. Yes, the angled T-plate ones sound just like the Sylvania GTA/B angled T-plates - and why wouldn't they, it's the same tube with a different base. I happen to think these are quite nice, but I like the 6SN7 version too. I've also got some that are parallel plates that I haven't yet heard, but I expect they will sound just like their SN counterpart. I also have some angled T-plate ones with a halo getter I've not yet heard. All of these, by the way, are chrome tops. Incidentally, I have it on good authority that ALL 7N7, regardless of how they are labeled, are made by Sylvania EXCEPT ones made by National Union which have grey glass, apparently very rare. And this is where it gets fuzzy, but exciting for me. I have several pairs of 7N7 that are grey glass, chrome top and parallel black T-plates. Most markings are gone or difficult to guess at, but a couple are marked RCA and one looks like Sylvania. So if these tubes are NU, which it would seem they are, it's funny that Sylvania being "king" of the 7N7 would buy and stamp some them with their name. But I can find no reference for Sylvania making grey glass 7N7. Anyway, are you still reading? Because they sound very, very, very good. They are in my top three tubes alongside 6SN7W and Meltz 1578. In fact, I think they are the equal of the W. The midrange is slightly forward of the W, it has all the air and fine top end without edge or glare and has arguably better bass. Better - more real, less highlighted - bass than the Kenrad VT-231 in fact. The KR does kick but it's artificially pronounced I find. This is just as deep but better balanced. Very sweet tube and I'm on the hunt for more. Shh, don't tell anyone... Cheers, Robert
Robert, just a side note, the wait for tubes from Andy is now 6 weeks. I ordered Ken Rads, called after 4 weeks, called after 6 weeks and received them later that week.
These are the coveted grey glass NU, no flash on top. So you've got something very special. Working link... National Union Gray Glass US Navy CNU 6SN7GT Tested 100% Pair in White Boxes | eBay
Right, I would love to try those NU grey glass out and it's highly likely they are identical to the NU 7N7 except the base obviously. These are the ones I have a few of and am loving. I guess they must not be NU as it's not likely their 7N7 would have chrome tops when their 6SN7 version doesn't. So these are probably Sylvania then. Cheers, Robert
I tend to agree that yours are Sylvania. I have no idea how NU is involved, but those I linked to use a bottom getter. They look like my NU black glass. Maybe you've seen this, I'm sure Sylvania made some of these that were rebranded.
Yes, I've read that before, the site is a good resource. I would say everything there is Sylvania, the internals match perfectly with their early GTA and late GTA/GTB. The two types I have that are somewhat different are these grey glass ones and the ones with the halo getter, the rest are square foil getter. The reason I mentioned NU was because I had read a couple times that they were the only other manufacturer of 7N7 and theirs were grey glass. But now seeing that their 6SN7 grey glass is a bottom getter, I'm guessing their 7N7 would be also. So not likely what I have. Cheers, Robert
Hello, I am new here in the forum. I've been working with tubes for just under a year now, and I'm sure there's still a thing or two to learn. But I am approaching the matter slowly and carefully. I have a question about this tube, the pictures are not so great. Plate is sometimes black, sometimes grey, probably due to the light. Rumour has it that grey is American and black is Japanese. Now what if someone knows? A US WESTINGHOUSE 6SN7 GTB TUBE IN ORIGINAL BOX. Ring Getter Silver Top | eBay
Gee, that's not one I would recognize easily. Flat, ribbed plates with no extra support rod. Top O (or halo) getter, rectangular micas. My guess would be a mid-60s RCA. GTB are not typically in the highest demand but I bet it would be a decent tube without a lot of character - which can be a good thing in some cases. Cheers, Robert
Hello, Thank you for your feedback. According to Brent Jessee's text about 6SN7s, the Gtb's and if they were built in the USA, they are not bad. I got that much out of it. Unfortunately i can only see that it was built in 1964 on the print and the number 337 supposedly says that Westinghouse really built it. Otherwise I don't recognise any features. I was hoping that someone might know more about it. As is so often the case, I'll have to give it a try and judge for myself. Is there anywhere else where you can documented about the 6sn7 back then? Surely patents, magazines and so on were registered or reported somewhere back then. What is important for us today about the small talk of the smartphone was certainly talked about back then about the tubes among the men.
