Replacing The Stock EH 6SN7 Tubes For Cary SLP 05

Thanks Rodman,

Do I stick to the +/- 5% tolerance level in tube strength test levels for tubes that are manufactured around the same period? In other words, if I follow this, can I purchase loose tubes and then match them and adjust for imbalances using the balance controls on the pre?

The reason I'm asking is because many of the listings on eBay are for single tubes or multiple tubes that seem to be "loose". Even a lot of them that are said to be matched pairs have different appearances, date codes, labels, etc. but are said to be electrically matched.

I guess it's unfortunate that tube buying at reasonable prices seem to be a crapshoot.

Most of the 6SN7 family tubes that I've purchased, have been in matched pairs. They are worth the wait and cost. Avoid any, that claim to be matched, but are not the exact same tube(internal appearance). A difference in presentation, between your channels, is almost certain to result. I've bought pairs that were identical in appearance/internal structure, but labeled differently(ie: Sylvania 6SN7W/6SN7A), and had differing date codes, but were perfectly matched in sound and electrical measurement. The 5% figure is a good one. Also, the triode to triode balance should be close, for each tube. Buying loose tubes, from different people would be a crapshoot, given that few tube sellers will have the same tube tester, and if they did; how close would the calibration be between them?

I have no affiliation to Brent Jesse other than as a customer, thought this link to his 6sn7 webpage might give you so insights on various tubes

http://www.audiotubes.com/6sn7.htm

I use several 6SN7's in my Atma-Sphere MP-1 and MA-1s(20 total) plus two in my Modwright/Sony 5400 and two more in my Cary SLI-80 all-triode F1. I've accumulated at least 70 or 80(lost count) NOS 6SN7's over the past few years including all the ones mentioned above; several Tungsol black glass, red base RCA 5692's, gray glass RCA VT231's, nickel base Sylvania's, you name it, I've got it.

Rodman99999 gave you lots of good advice. I too love the old Tungsols and while I wouldn't describe them as lean like many of the Sylvania's, they are pretty neutral and won't add much warmth. If your Cary can handle the red base RCA 5692's, that's where I'd be looking; a very sweet tube, big spacious airy soundstage and images with plenty of flesh on the bones. If you're nervous about getting non-microphonic matched pairs(I would be) at the prices they're going for, you may want to just look into some later RCA GTA's or GTB's. They're still plentiful and cheap and they'll definitely give you what you're looking for.

Be careful if you're looking at TungSol black glass, RCA 5692's, RCA gray glass(GT or VT231) and the KenRads. Many of them have been recycled on Ebay and can be VERY microphonic. Id get some kind of guarantee if you spring for any of them OR, buy from a reputable dealer who'll give you a guarantee; Andy at Vintage Tube Services comes to mind.

Also, for the money, while the Black Treasure and Psvane's are supposed to be very good, you can probably pick up NOS RCA's for less and they'll most likely sound at least as good, if not better, AND I'll wager they'll last a lot longer than the Chinese tubes.

Finally, Rodman is exactly right about those Mullard/Blackburn GZ34 rectifiers. They sound great, last forever and it's fairly easy to find good reliable ones on Ebay or the 'Gon.

Ken Rad Black coated glass VT231 = 6SN7
http://www.upscaleaudio.com/tubes/6sn7/kenrad-vt231.html

Brimar CV1988 = 6SN7 with print on glass, not base, with O getter on bottom - My favorite
http://vintageaudiovalves.com/miscellaneous

GE/CBS Hytron 5692 - another great choice. I have GE branded.