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There were some concerns about reliability of this tube from old posts that I searched. Is it still the same?
How is the tone of this compared to a EH EL34 or 6ca7? I am thinking of replacement of the power tube which is EL34.
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I.D.
Follow Ups:
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.
I run one of each type on each side when I have mismatched pairs like that.
In one instance, my pairs were actually different 6BQ5's. A GE 6BQ5 with a Sylvania 6BQ5 per side mixes much better than GE x 2 on one side and Sylvania x 2 on the other side.
In the other instance I had two 6L6WXT's with several hundred hours on them and I used them with a brand new pair of 6L6WXT's for a quad .... one of each per side.
Thanks ecline6 for the suggestion. When I get around to it I will try it as you suggest. But its hard to get the EI KT90s out of the amp, they have been in since the end of December and have temporarily cured me of output tube rollingitis.
Ahoy hoy!I have experienced tubes from JJ and New Sensor. I abuse the living snot out of my tubes. Reliability is a funny thing... My JJ KT77's have been pretty solid, but I think one of them juuuust went bunk in a HiWatt DR105 :( That said, I had one Gold Lion KT77 which would glow a bunch under load; I don't think it liked the high voltages of a 71 Superlead.
(Tube) - (Failure rate) - (Remarks)
I have had a selection of following go bye-bye on me:
- JJ 6CA7's - 2/6 - flaw in the base of the glass (took in air), and hot glow under load (500+V)
- JJ KT88 - 1 out of 12+ - flaw in the glass but really solid overall - design has changed lately, has anyone noticed? I'll try to get two tubes to compare. These have stood up to the molestations of a Marshall Major and Fender 400 PS which I think is nothing to scoff at.
- JJ KT77 - jury is out to lunch on this - I'll report back another day
- JJ E34L - Not bad, no issues yet, and they're so cheap I don't mind throwing them at people lol
- Sovtek 6550's - all of them! Pieces of garbage! Couldn't even survive a hot-rodded BF Bassman. Tisk tisk. Big glow under load.
- EH KT88 - 1 out of 8 - flaw in the glass, but fantastic value for what you get - great after some breaking-in to get rid of the edginess
- SED 6550 - no problems
- SED 6L6GC - no problems
- Gold Lion KT77 - 1 out of 5 - may have been just a fact of high voltage and needing a cherry-picked tube
- Penta KT88SC - 1 of 4 finally blew out after a year(+) of abuse.JJ CAN be good. But, the issues people have with them are not vaporous. You need guaranteed a load-tested set if you go JJ - CHECK THE GLASS under some light. The only tube that I have had no issues with is their OLDER KT88's. I don't have experience with newer ones. Out of newer JJ's, I have used the KT77's and 6CA7's - not stellar so far for reliability.
Btw, for tone difference, the KT77 has a much more present mid-range and high-end bite, but sounds slightly brittle which can give it a bit a cruddy presentation. 6CA7 sounds a little fatter and level but nice and clear, easier to listen to but not necessarily as lively-sounding as the KT77. AFTER ALL THAT, the Gold Lion KT77 sounds like a mix of the two but with the best of both worlds and none of the bad, you lose the brittleness and you keep the liveliness without getting ear fatigue, and on the side you get this little added "soul". Hmm...
I hear New Sensor's Electro Harmonix is associated with the better half of the old USSR's skill, engineering and tooling. There's a great deal of quality to EH's stuff I find. Their KT88 is a good staple tube. You may find the EH 6CA7 is worth checking.
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May your tubes be lively and long-lasting. Holy be thy heater.
Edits: 03/17/14 03/17/14
There are reliability concerns about all of JJ's Octal based production. :> ((
JJ knows how to make good tubes. In past, that was shown any number of times. However, their product of the last few years leaves much to be desired.
JMO, if you want KT77s, buy "reissue" GEC labeled tubes manufactured by New Sensor at Saratov, Russia.
Eli D.
When you say reliability concerns, you are saying the tubes fail? Is there any chance of damage to the amp?
I have used JJ EL34s in the past and it has failed twice now that I recall.
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I.D.
Si!
You'd be MUCH better off with these including that they sound better:
I've experienced both.
"Once this was all Black Plasma and Imagination" - Michael McClure
Thanks! I wish they were not so freakin' expensive!! :-(
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I.D.
but then there were reasons that changed:
1. Sound quality.
2. Overall quality.
3. Piece of mind based on #2.
4. Ever seen the price of originals?
They're a deal by comparison!!
(oh oh, compared current production tubes to vintage tubes I've never heard...)
Anyway, they may seem expensive, but they are worth it IMO.
"Once this was all Black Plasma and Imagination" - Michael McClure
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