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RE: JJ KT-77 question

I have used the JJ KT77 and the EH 6CA7 of the tubes you mentioned. I have used the JJ on and off for about 3 years raking up maybe 1000 hours. I have had no problems at all with my quad, they hold their bias very well with little drift and still sound as good or better than when I first got them (from thetubestore.com).
I bought a quad of EH 6CA7 from the same source at the same time and also ran them on an off for about a year (maybe 250 hours) until I had problems with bias drift and noise in two of the tubes so I stopped using them. When they were working they were a good sounding tube, but I always prefered the JJ's. The JJ's are a very alive sounding tube, lots of dynamics and clean detail in the mids, great extention top and bottom. Slightly thin sounding (but not hard) I would usually pair them with warm diver tubes (in my case 6SN7) like the RCA VT-231. The EH 6CA7 has a big, meaty sound to it, but I felt it was harder sounding in my amp.
Lately I have had intrest in trying the EH 6CA7 again so I purchased a pair last month to use with the (almost new) good pair I still have. I was surprised to see that the two pairs are not exactly the same structurally. The (heat) wings on top of the top mica are much larger in the newer pair than the tiny ones on the old pair.
I am wondering if I really have a quad here or if the tubes are different. Have not tried them yet and was wondering how to use them. I could run the different pairs together on each side, run one of each type on each side, or order two more to make a quad (provided they have not changed again). Open to suggestions.


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