6SN7 tube GTA vrs GTB

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. :)

Thanks-