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I'm kind of completely turned off of JJ tubes now

172.58.184.87
Posted on April 26, 2017 at 06:54:00
DewDude
Audiophile

Posts: 157
Joined: February 13, 2002
 Some of you may remember me a couple weeks ago asking suggestions for new 6V6 tubes after one of my JJ tubes decided it'd rather make a light show.

Another one has failed now. This time no light show...but it was causing the resistor in the power supply that feeds the 330v supply to burn. I took it to the shop...caps were fine....no shorts in the chassis, but the cheap Eico never indicated a problem with the tube. But minute I powered the amp up and the filaments warmed up...it was trying to let the smoke out.

Stuck a different tube in...no more smoke. Ran it for five hours and not a hiccup.

I think I'll buy new production Tung Sol.

 

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RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 07:51:12
TubeAcolyte
Dealer

Posts: 366
Location: Ottawa, ON
Joined: December 13, 2009
 I work entirely with guitar amps, and I kinda feel you on JJ tubes. My experience has been mixed as well. I have had pretty good experiences with the small tubes. But, power tubes seem sensitive to higher voltages. I've had some work great, mainly the more robust KT88. Others (25W to 30W tubes) seem to fail more easily when subjected to the higher-than-usual voltages.
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May your tubes be lively, warm, and long-lasting. Holy be thy heater.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 07:58:51
krankkall
Audiophile

Posts: 296
Location: New Mexico
Joined: April 5, 2014
 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?

Steve

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 08:14:32
Eli Duttman
Audiophile

Posts: 10455
Location: Monroe Township, NJ
Joined: March 31, 2000
 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.


Eli D.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 08:23:49
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 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.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 08:27:27
Hornlover
Manufacturer

Posts: 2529
Joined: March 8, 2002
 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.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 10:43:05
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 That's not unusual either. The only 9 pin JJs I trust are the ECC99, the ECC832, and the EL84.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 11:23:37
DewDude
Audiophile

Posts: 157
Joined: February 13, 2002
 Well, it sounds like I'm not the only one. There was a series of events that has lead to this, so perhaps I'll give a background.


I bought these amps in autumn of 2011 on a whim. I was looking for my first tube amps and fell in love with them. They had the JJ 6V6S tubes in when I bought them. Ran fine for three years.

I then decided to swap in a pair of the Reflektor 6P6S tubes in each. They didn't die and ran for two years. One developed what I think is called hot cathode. Tube still works...but the entire cathode glows. That was when I went back to the JJ tubes.

Things were fine for about six months...then one amp developed low volume. The 5y3 was cold...so I swapped in a new pair. Then after discussion here....I ran something else because I liked the big bottles.

Two weeks later...a 6V6 dies...internal arcing. So I had a good pair of JJ and a good pair of Reflektor..so I stuck one of each in the amp and ran it.

No problems till Monday night. The amp was crankin out tunes....no problem. Then it quit. This is no big deal as I have a PITA interconnect I sometimes have to tap. That wasnt is...amp was dark. Fuse popped with smoke billowing out.1.2K resistor cooked.

So I took it to work and checked the caps and transformer. Not there. Our Eico said the 6v6 tube was fine.

Nope. It started smoking the minute I turned it on. Pulled the JJ and everything was fine.

Threw tube in the trash.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 14:06:08
Todd A.
 How do you feel about the 2A3-40?

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 14:11:52
Alpha Al
Industry Professional

Posts: 2958
Location: N. Carolina
Joined: February 16, 2004
Contributor
  Since: December 3, 2015
 "Our Eico said the 6v6 tube was fine"

First, did you do the shorts test? It's not easy on an EICO, but you can test for shorts.

If it passed the shorts test, it was a short that only occurs with high voltage present. Testers test at approx 150V, amps run the plates and screens at 400+V.

Usually, in 6v6 types, it's a screen short.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 15:25:17
Orchardist
Audiophile

Posts: 830
Location: NH
Joined: April 6, 2003
 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.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 26, 2017 at 16:50:45
DewDude
Audiophile

Posts: 157
Joined: February 13, 2002
 The short test on this was merely moving the indicated knob to the indicated position. This was the first thing I did. It only had one test listed....so it was probably a screen short. I can't remember which Eico tester it is...my boss swears by the thing, I mostly swear at it.

If the workshop trash hasn't been emptied tomorrow and I can remember to do it; I'll retrieve it and put it through my Precision 612...which will short-test everything. Not that I really care...tube had a problem and was bound for the trash can anyway.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 27, 2017 at 03:37:12
SETdude
Audiophile

Posts: 3944
Joined: January 20, 2000
 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?

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 27, 2017 at 06:45:29
FenderLover
 I never really liked the tone of the JJ 6V6S. I've been replacing units with new TAD 6V6GT with pretty good results. FWIW...

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 27, 2017 at 11:00:12
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 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.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 27, 2017 at 12:55:35
DannyR
Audiophile

Posts: 611
Joined: January 21, 2001
 I'll try those next time. The only thing that I liked about the JJ's were they could take a lot more voltage. I've seen people pop em in marshalls even.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on April 27, 2017 at 13:09:17
TubeAcolyte
Dealer

Posts: 366
Location: Ottawa, ON
Joined: December 13, 2009
 Been there, done that. It's a half-and-half thing. The plates can take it, no problem. And, newer Marshall are fine, right up into the 70s era; they typically run some 450V. It's the mid-late 60s Super100 and JTM45-100 Blackflag amps that get weird as they run some 500-600V and hit peak outputs of 200W RMS.
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May your tubes be lively, warm, and long-lasting. Holy be thy heater.

 

This is the part I don't understand., posted on April 27, 2017 at 21:45:30
Michael Samra
Dealer

Posts: 36118
Location: saginaw michigan
Joined: January 30, 2005
 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

 

RE: This is the part I don't understand., posted on April 28, 2017 at 12:04:38
Jim McShane
Dealer

Posts: 5910
Location: Chicago
Joined: January 13, 2003
 "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.

 

RE: I'm kind of completely turned off of JJ tubes now, posted on May 25, 2017 at 12:37:01
Audio Pete
Manufacturer

Posts: 152
Location: Long Island,NY
Joined: May 22, 2015
 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?

 

RE: I'm kind of completely turned off of JJ tubes now, posted on May 26, 2017 at 17:30:03
TubeDriver
Audiophile

Posts: 794
Location: East Coast
Joined: February 16, 2007
 I have used several pairs of JJ 300BS, no issues at all. They last 3-4 years of several hours each day use, sound ok and are inexpensive.

 

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