6SN7 tube GTA vrs GTB

I would like to know the difference between the designation GTA and GTB.

GTA: Max Plate Watts=5, GTB: Mpw=7.5
GTA: Rp=7700, GTB: Rp=6,700
Plate Current: GTA=9 mA, GTB=10 mA
The GTB was developed to handle 450 volts on the plates the earlier GTAs and GTs should really be biased down to 350 Volts. As for sound Only your ears will count. That said the GTB tends toward the warmer side and work well in an analytic system otherwise. The Old Stock 6SN7s are reasonably priced unlike everything else for audio and not including obscure Ham tubes. I would try a few different 6SN7s don't omit the GTs.
The GT are favored by many including me, the WGT is a tougher mil spec variant that I like as well. The Gts are popular and the demand is relatively high the good news is the the supply is enormous, thus fair pries. I have read that the 6SN7 was favored by the engineers due to their linear behavior. They were widely applied and many "millions" are out there. There is excessive demand for some of them, they are good no doubt, but the tube dejour are royally expensive.
I am not sure of what you consider "royally expensive", but I think I agree. I just paid $60.00 each for NOS Sylvania 6SN7s that are supposed to be "the" thing. I hope that they are worth it when they arrive.

Very good info... many thanks for sharing your knowlege!
(http://home.att.net/~chimeraone/6sn7sound.html) I'm using the TungSol JAN CTL/6SN7GT bottom getter, round plate(not the mouse-ear) from the 40's as a driver and the Sylvania JAN CHS/6SN7W tall bottle(avoid the short bottle like the plague) as a phase splitter in my modded Cary SLM-100's. Couldn't be more pleased with the accuracy/dynamics and pure music that results. The less expensive but still excellent sounding alternatives are the Sylvania and Ken-Rad VT-231's(both 40's, bottom getters). That's if you enjoy clean, uncolored, no extra sweetening/warmed up sound. Otherwise the Raytheon, National Union and RCA VT-231 offerings may better suit you. Happy listening!
Keep in mind if looking at the Sylvania JAN CHS/6SN7W(tall bottle, metal or black base): Some will try to pass off 6SN7WGT, GTB, or GTA's as the same tube. They're not even close in sonics. IE: (http://cgi.ebay.com/Two-1943-Sylvania-6SN7W-VT-231-6SN7-tube_W0QQitemZ320270099754QQihZ011QQcategoryZ73380QQssPageNameZWDVWQQrdZ1QQcmdZViewItem) CAVEAT EMPTOR!
It has been a journey for me to search for the "perfect" 6SN7s. I have 3 amps that use 6SN7s, and I tend to use GTAs and GTBs for driver tubes only. I have the following tubes for the gain stage and my summary is as follows:

Sylvania VT231s, bottom getters: clean, fast, accurate, and airy. My choice for classical music, but a bit thin for vocal music.

RCA VT231s, smoke glass: rich harmonics and sweet sounding, but a bit slow. It is great for vocal music, but not for complex classical.

Raytheon 6SN7GTs: nice sounding, but a bit too sweet for me

RCA 5692 Redbase: fast, rich, dynamic. It is excellent for Jazz and vocal, but not as good as Sylvania VT231s for classical music.

CBS 5692 Brown base: a tuned down version of RCA Redbase.

Ken-Rad clear glass: a bit too euphonic for me

Ken-Rad black glass: strong bass, but does not have the airy magic

Sylvania 6SN7GTs chrome top (not to be confused with GTA chrome top): my current overall choice, they are as fast and airy as Sylvania VT231 bottom getters, but have more sweetness.
I use Sylvania GT's and the ones known as (Bad Boys)in my pre. I can not find better.
(http://home.att.net/~chimeraone/6sn7sound.html) I've personally verified the findings of this site. That's why the TungSol JAN CTL round plates, and Sylvania JAN CHS/6SN7W(tall bottle) tubes have found a home in my system. None can deliver the music with less harm than they.
Looks like I will be starting some more tube rolling in the near future.

I've been wanting to try some Tung Sol round plates..I use the Pope Holland's now. Thoughts?
Hello Mr J- I've never listened to Pope Hollands, so I can't offer anything in the way of a comparison. Do you enjoy a very uncolored, alive presentation or something more euphonic/tubier? The TungSol, Ken-Rad and Sylvania tubes I mentioned will deliver whatever comes out of your source with a minimum of alteration(very transparent/uncolored). Some listeners enjoy a bit of added sweetness/warmth. If that's your pleasure: The Raytheon, RCA and National Union VT-231 tubes still produced excellent sound staging, imaging, dynamics, etc but with just a touch of added warmth. I suppose, in a system given to strident highs: that might be beneficial. My suggestion would be to try a pair of the Sylvania bottom gettered VT-231s, and if they appeal to your tastes- buy a pair of Tung-Sol round plates. They just have more of everything that's good in the Sylvanias. Where are you located?
OK. I've tried NOS RCA GTB's and never liked them. I am in Charlotte, NC. You?
That would be a little too far to drive. I'm in Indy! I thought perhaps I'd bring my tube collection over for you to try, before making any purchases. Here's a pair of the correct Sylvania VT231/6SN7GT tubes from a seller I've dealt with and trust very much: (http://cgi.ebay.com/Sylvania-6SN7GT-6SN7-VT-231-VT231-matched-NOS-pair_W0QQitemZ120282753596QQihZ002QQcategoryZ64629QQssPageNameZWDVWQQrdZ1QQcmdZViewItem) Angie and Steve are in Australia, but get their tubes to you very quickly. If you can get those cheaply enough, and like them: The TungSol roundplates will REALLY make you happy! I'm saving a couple pair for when the TungSols and Sylvania 6SN7W's disappear altogether.
OK. I will check that out. Funny, I will be in Indy in two weeks for work....
Too bad you can't bring your system(and listening room) with you. Given so many variables- Tubes that sound perfectly natural in my system, could sound much less so in yours. I've a feeling you'll like the Sylvanias and TungSols though, and the VT-231 will be a less expensive foretaste.
how are the Sylvania 6SN7WGT that good? I was told they are GREAT. Is this true? The "best" 6sn7? How do they compare to the RCA GTB's?

The "best" are the 40's TungSol JAN CTL/6SN7GT round plate, bottom getter and Sylvania JAN CHS/6SN7W(tall bottle, metal or plastic base)- hands down(that's IF you like transparency, dynamics, extension on the top and bottom without glare of tubbiness, imaging, microdynamics, depth and width of sound stage). The price that these tubes command reflects the quality of their sound, and the number of persons that appreciate it(very high demand). Of course: Some enjoy a more colored(warmer, sweeter, tubier, etc.) sound, and may prefer other tubes. The 6SN7WGT is a good tube but not nearly "the best"(though probably the best most have tried). The RCA's have a "warmer/fuller" presentation in most equipment.
Make that: glare OR tubbiness(typo)
You happen to prefer the most commonly sought after royally expensive 6SN7s. I own three pairs of CTL Tung Sol RPs I really do. I have a few Ws as well. Both of those cost about $400-500 a pair. The market is starved for them. I used them for a while in my preamp and concurr they are superb no arguement there. I think that less coslty alternatives serve me almost as well. I have a very big collection so I change them around from time to time. The only tube I never really sought after was the 5962 I have 2 pairs and gave away 2 more Yes I did. The 52 Bad boys were also produced in late 51 and early 53. Not all Sylvania 52 GTs are bad boys btw. The WGT is a very fast tube that is neutral enough and if you look carefully resemble Ws in their construction. They are all short bottles which are not considered dreadful by the market.
As far as W's go, I have tall and short the tall wins but I wouldn't go so far as to call the shorts to be avoided like the plague. What did you find so aweful about them.
In any event the RCA VT231 in Grey Glass are well liked for their fluid,sweet, some say lush sound. The latter RCAs are all servicable but not outstanding. The Brimar GTs are quite good but a tad to euphonic I am sure for some. I don't have any other Euro N7. The 2 Raytheon types, the Hytron, and CBS, the Ken rads non bad Boy CHS vt231 Sylvanias, the various GTBs. All of them have very characteristic sonic signatures no they are not those Tung Sol GT RPs not as great as the W's.
Those less than great tubes, to certain people, though are not royally expensive and provide plenty of other great tubes to try without resorting to the acklnowledged no brainer top picks of Tung Sol Round Plates.
Yes TS RPs are truly excellent as are the W's. If you can't spend $500 for your N7s the truly smart buyer will find a tube that suites them for less. There is no point to keep pounding at the obvious. It's akin to saying that the best turntable is the Galiber or the Walker -we all know OK. Anybody want the best tubes I have mentioned for free? What's this? everyone who owns a N7 amp wants them, Geeze I would never have guessed. Sorry I don't have enough to go around Oh Well.
One thing that I suggest, is to buy from a tube dealer that will test for microphonics. 6SN7's are prone to be microphonic and noisy ones will obscure detail. The ones you buy on ebay are probably not sorted as to how noisy they are. Vintage Tube Services will have quite tubes as well as some other web based tube venders.
Hello Mr M: I suppose the value of those tubes would have to be judged by one's love for the sound of music. I thought nothing of spending $1300.00 for a pair of Kimber KS-1130s for the transparency they afforded me(two years ago), and $680.00 on upgrading the power supply of my pre-amp for a bit of added dynamic range(last month). The Tungsols(driver) and Sylvanias(phase splitter) in concert yielded an even greater reward in terms of pure resolution, sound staging(width and depth), dynamics and timbre. To me they are a bargain, as is anything that brings me closer to the music. In a system less modest(more resolving) than my own, I'm certain they would provide even greater rewards. You did manage to restate what I said about not losing much by seeking out the lesser(and lower priced) VT-231, 40's, bottom getter Sylvanias and Ken-Rads both of which I have in reserve in quantity. Regarding the short bottle 6SN7W: In direct comparison to the tall bottle, it was much more strident(highs), thin in in the mid-range and dynamics were lessened. It made vocals sound Hi-Fi rather than live(tinny with no immediacy), and cymbal crashes sounded like breaking glass rather than resounding bronze(Sabians and Zildjians). I imagine on a system that was lacking in definition, they could be considered somewhat of an asset. Thank you for qualifying my earlier posts regarding the colorations of the other still great and well-received NOS tubes of this family. The price that "the best" 6SN7 tubes are commanding shows that there are those out there that feel as I do, and value the music more than the money! I don't see any reason to avoid extolling their virtues. Happy listening!
Having them tested for noise is VERY important/imperative if they are to be used in a pre-amp, mic or phono stage. MUCH less so in power amp circuits.
Well I am happy to have finally sorted through enough N7s to have all of the TS RPs in one tray which has a bunch of other fairly good to superb ,no not the TS level tubes.The bad news or good news depending how you see it is that this is not even close to all of them.I have atray of RCAs the good the medium and the not so great IMHO. One tube a l only single is just called a CCA not related at all to 6922. It is definately an RCA with a CRC marking.
I have had the experience of dead silent tubes become microphonic it is in the non reinforced architechture. Curiously I never hear the whine or ringing people describe. I do have a resolving analytic system which will show warts and all.
The dealer cannot promise that even the most rigid will stay non micrphonic. What they do is better matching for gain etc and intertriode imbalance. These are like any twin triode one can be more than 10% different than the other. This does have a measurable effect but again you have to be looking for it. I know because I have had pairs that weren't close and used a SPL meter to measure the difference it is there, but not obvious.
Has anyone heard of the 1578-6SN8 tubes from Russia? If so, I would like to know what you think of them.

I like all this tube talk. :)