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In Reply to: RE: I'm kind of completely turned off of JJ tubes now posted by DewDude on April 26, 2017 at 06:54:00
I'm running a new matched pair of JJ EL84 tubes, in a parts bin DIY RH84 SE amplifier.
So far, I am liking what I hear....but...., I am worried when I read about a lack of QC/reliability in the JJ brand?
Don't worry. There were issues in the past but no more. You still need to source them from a solid vendor.
How many of the negative responses are from recent experiences?
JJ's Noval (9 pin mini) tubes are OK. It's the Octal based types that are highly problematic. Rest easy, JJ's EL84 is 1 of their better efforts.
I have been running JJ KT77s for about a year now in my Dyna ST-70 without any problems. The ECC83s are good too as well as my EL84s. Sure its not a screen grid problem because of the lack of screen grid resistors in series?
I have had JJ 12AX7's fail on the test bench after just a couple of hours on them. They were running very conservatively, so I know I didnt over tax them.
That's not unusual either. The only 9 pin JJs I trust are the ECC99, the ECC832, and the EL84.
Yes, what Eli said! The EL84 JJs are good. The octal tubes - not so much.
For you guys who buy tubes from me and other good vendors - keep in mind that the good guys glean out the problem tubes before they send them out to the purchasers. So of course your experience is better since the tubes got a final "QC" check before you got them. But failure rates of up to 50% on JJ octals is what I would routinely experience. Yes - when you got the tubes they were good performers because my colleagues and I took care of the trash for you. But nobody can afford to have the kind of failure rates I was having with JJs.
Having said that I still won't use the octals in my own gear - therefore I won't sell them.
But the EL84s are fine.
JJ can build fine sounding tubes and this for the Octals as well when they work.I still question where the Octals are coming from that feed the US market. McIntosh has JJ making the KT88s for the Mc275 and the Mc75 as well their huge mono-blocs. They used to have SED make them.
Jim,if you remember first the JJ KT77s that came in from CE,many had crooked bottles,flashing in the wrong places,and under sized pins.It was like somebody went to JJ and raided their reject garbage bin and hauled them back to the US.
I talked to Tomas at JJ and he was totally unaware of the bad tubes and he ran the whole factory. That made me think that there has to be an issue of some sort that may resemble that.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
"I talked to Tomas at JJ and he was totally unaware of the bad tubes and he ran the whole factory."
I wrote back and forth to him, and he denied any problems existed. He also said they had quality equal to Tesla (their predecessor). It seemed to me like they had their heads in the sand and fingers in their ears..
Someday I should post my email to JJ and Tomas' reply. I do have permission to do so.
I value your knowledge highly. You are right about a vendor carefully screening JJ tubes to weed ( burn ) out the tubes destined to fail. I have been back with JJ E34L for the last 3 years or so which I had always bought from you prior to the QC issues.I am not going to name the vendor, but I have not had a single tube fail prematurely. They just fade away.
That's exactly my point - once the junk is weeded out as the end user you can often get a decent set of tubes - as you have found. But to have SO many failures in screening is simply too costly for many vendors to deal with. And I sure as heck would never send out JJs that were not very carefully screened!!
I can do the same thing your vendor can - as long as I am willing to deal with all the duds and the time and expense that is the result of having so many failures.
How do you feel about the 2A3-40?
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