Best kt88 for VAC Avatar Super

IMO, the Shuggie Black Treasures (KT88-Z) trump everything but the EAT's and the NOS (vintage) Gold Lions. They are as good as the vintage GL's (per my own A-B) and may be as good as the EAT's. They definitely exhibit what I call 'high transconductance sparkle', like the EAT's and the NOS GL's.

Their only negative (not really, but . . .) is they take the FULL 300 hrs. to break in! Probably for the black carbon polymer coating to cure? And no one knows (yet) how long they'll last? I've been running mine for 2 yrs come Feb. (about 3500 hrs.) If you buy them direct from China, you can get Premium matched Treasures for under $400 for 2 matched pair, shipped ;--)
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Shuguang makes the following KT88 tubes:

KT88-Z (Black Treasure)
KT88-98
KT88-SC (Penta)

BTW, the 'SC' is the only KT88 tube currently made (by anybody!) that is an EXACT replica of the original M.O.V. (Marconi Osram Valve) Company later known as GEC or Genalex (the British name of the US General Electric Co. ;--) who bought MOV and made the original Gold Lion, Gold Monarch and Blue Label GEC (all the same tube, BTW) The Penta/SC is an excellent tube, but nothing like the original performancewise.

The "Gold Lion" tubes currently made by New Sensor (in the old Russian Sovtek factory) bear no resemblence to the original design -- a statement that can be made for most of the tubes New Sensor manufactures under all the vintage brand names they managed to acquire (Mullard, Tung Sol, Svetlana, et.)

As for Kevin's recommendations, with due respect, equipment manufacturers use tubes which represent a reliable supply for them (followed by reasonable cost) but are not always the 'best' tube of that type. Sometimes their OEM tubes cause problems, as with McIntosh's use of the New Sensor "Electo Harmonix" brand (which kept blowing up ;--) McIntosh finally switched to the S.E.D. Winged "C" KT88 (the original Svetlana tube, not the New Sensor brand "Svetlana" tube ;--) which is another excellent KT88 tube.

Bottom line is that if you want to do a little research, you can almost always find better tubes for your equipment than the OEM tubes supplied by the manufacturer.

Clio, all I can say is it might be instructive for you to talk with other VAC owners who have tried other tubes in their amps ;--)
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FWIW, nobody really NEEDS a matched quad ;--) Push-pull amps (the most common) work in matched pairs. However, if your amp takes four of something, or eight of something, then there are certain economic and operational advantages to buying FIVE matched tubes (for each group of four):
1.) You don't have to keep the matched pairs separated. You can plug any tube into any of the four sockets and still be running two matched pairs.
2.) If you buy FIVE matched tubes, then should one fail, the fifth (spare) can replace any one of the four that fails. If you're particularly O/C, you can even rotate the five (like tires) so thay all have the same 'wear'. (This may sound silly, but tubes, especially power tubes, DO change their test readings over time, even though they are still performing just as when new.)

To the question of breaking tubes in 24/7: I don't recommend it. It won't harm the tubes, and back when there were ONLY tubes, a lot of gear was left on 24/7, sometimes for years, for various reasons, with no ill effect. But with NEW tubes, it's best if you are present, with your hand near the on/off switch if fireworks should start -- which they most often will in the beginning -- usually right after turn-on, or as the tubes are warming up. With a few exceptions, most power tubes are substantially 'broken-in' (and can be pronounced 'reliable') after 25 -- 50 hours. That's only a dozen listening sessions at most. And with a lot of power tubes, you won't actually want to 'listen' for the first 25 hours anyway ;--)
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Lrg36, GF will push anything (they think) they can monopolize, as it was with the Black Treasure series, in the beginning, when they 'claimed' they had 'exclusive' North American distributorship for the Black Treasure tubes -- that is until everyone found out it wasn't true, and when at least one online tube seller I know brought legal action against them! So you can understand if I'm a bit suspicious about their (latest) story regarding the Psvane line ;~)

Mjcmt: I have been dealing with Clark (at Good Component) for over four years, and have sent him many very happy customers. You can even request that your matched premium KT88-Z's (Shuguang Black Treasures) have the strongest emission readings (greater than 50 mA) and if he doesn't have any on hand, and you're willing to wait a couple of weeks, he will hand pick them for you right at the factory when there's a new production run. Not only that, but he seems to have the best prices of anyone. The last time I bought a quad, they were $357 (for two matched premium pair), including PayPal and DHL airfrieght. That's what I call 'service'! BTW, Clark also sells Psvane tubes -- probably a lot cheaper than GF!
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