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Hi Doc,So you're doing a group buy for KT77 and N709 (N709 = EL84)?Thanks.
I can do the EL84 next month I guess.DC
I will do a pair of EL84's when available for a group buy. These are GREAT tubes. I don't have need for KT77's until I get my AVA UV70 amp NB
I can bias each power tube individually on my amp.I believe you can do the same on your Caying A-50T. Just follow the instructions in you manual.
One thing to keep in mind, the KT77 is a completely different animal than EL34. The EL34 is a pentode (usually run as an Ultralinear in a lot of amps) and the KT77 is a "Kinkless Tetrode". The only other tube I've heard from the KT family is the KT66. So the sound is very different among the two families of tubes. To me, the EL34 sound more lush and romantic and sacrifices a bit of detail for the smoothness. The KT tubes are hardcore. Plenty of dynamics and slam, better speed and a lot more detail. They also give a bigger soundscape than EL34. They have this "presence" that I haven't heard on any EL34.
What is Kinkless TetrodeFrom martin--(at)--houl.bri.hp.com Mon Feb 12 11:43:24 CST 1996From: martin--(at)--ri.hp.com (Martin Ackroyd)Newsgroups: rec.audio.tubesSubject: Re: What is a Kinkless Tetrode?Date: 12 Feb 1996 08:43:10 GMTReply-To: martin--(at)--houl.bri.hp.comb.stac--(at)--enie.com wrote:: I've heard that the "KT" in KT-66, KT-77, and KT-88 stands for: Kinkless Tetrode, and that this is somehow different from a : beam power tube.: Is there any real difference? Who came up with this idea?There is no difference. Same thing. Here's the story as I know it...In the 1930's, Mullard had the patents on the pentode, so otherfirmes had to pay royalties. EMI invented the beam tetrode as away to avoid paying the pentode royalties. But good ole EMIchose not to exploit it commercially. They had a patent sharingagreement with RCA, who immediately saw the potential and producedthe 6L6.GEC [the British General Electric company - nothing to do with AmericanGE] then decided to make an equivalent to the 6L6 and, in around 1937,produced the KT66, as a plug in replacement for the 6L6GEC got very enthusiastic about 'kinkless tetrodes' and used theprinciple to produce rf valves [KTZ63, KTW63] that were alternativesto the rf pentodes 6J7, 6K7.My dad was working at GEC on radio design at the time and the aboveis how he told me the story.'Kinkless' just means the anode characteristic does not have a negative-sloperegion ['kink'] like the original rf tetrodes from the early 30's had,caused by secondary electrons emitted from the anode, arriving at thescreen grid when the screen grid is more positive than the anode.[eg like in an output tube with big anode voltage swings]..Using a suppressor grid [making the tube into a pentode] is one wayto make sure secondary emission from the anode does not give the kink.Using beam forming electrodes plus careful alignment of electrode structuresis another way.To repeat: "Kinkless Ttetrode" = "Beam power tube". Same thing. No difference.-- Martin A.----------------------------------------------------From audioen--(at)--vpal.svpal.org Mon Feb 12 12:26:14 CST 1996From: audioen--(at)--vpal.svpal.org (Scott Frankland)Newsgroups: rec.audio.tubesSubject: Re: What is a Kinkless Tetrode?Date: 12 Feb 1996 17:34:18 GMTDistribution: worldb.stac--(at)--enie.com wrote:: I've heard that the "KT" in KT-66, KT-77, and KT-88 stands for: Kinkless Tetrode, and that this is somehow different from a : beam power tube.: Is there any real difference? Who came up with this idea?The kinkless tetrode is a beam power tube [1]. It differs from theordinary tetrode in the same way that other beam tubes do; i.e., itprovides a virtual suppressor [2]. Beam tubes differ from other beam tubesmainly in the manner in which the electron stream is formed; i.e., in theshape and position of the beam formers [3]. The 6L6 was the first beamtube [3]. [1] M.O. Valve Co. Ltd. tube specification, London, England.[2] O.H. Schade, "Beam Power Tubes", *Proc. IRE* Feb. 1938, pp. 162--176.[3] Richard F. Shea, Editor-in Chief, *Amplifier Handbook*, McGraw-Hill, NY, 1966.
I might be in for a quad. Will decide by next week. However I am certainly in for the EL84 whenever that happens.With regard to 'factory matching', I have found that it often don't mean a thing...
