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Post subject: Early JJ output tube failure.
Posted: Sat Mar 09, 2013 12:18 pm
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FYI, from another board (catastrophic failures):

Edit: Both failures shorted (heater windings) to cathode.

My "emergency" Sovtek's seem to last forever and really don't sound that bad either.

Anybody else having JJ KT88 failures? What a good mid priced KT88 these days?

Conditions: KT88 PP UL fixed bias running 40ma @ max 550v B+.


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Post subject: Re: Early JJ output tube failure.
Posted: Sat Mar 09, 2013 8:02 pm
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Beemer you allready know about my 6L6GC jj's that died, they had less than 10 hours of use. :roll:

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Post subject: Re: Early JJ output tube failure.
Posted: Sat Mar 09, 2013 8:44 pm
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Or my JJ Gz34, lasted less than 15hrs. But at least it lasted longer than the sovtek, maybe 2 hrs.

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Post subject: Re: Early JJ output tube failure.
Posted: Sat Mar 09, 2013 9:03 pm
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Seems like the only 5AR4 being made today
Worth using is the TAD
I've had good luck in a few DRRI's with them

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Post subject: Re: Early JJ output tube failure.
Posted: Sat Mar 09, 2013 10:23 pm
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My JJ 5AR4/GZ34 has been in my 5F6A clone for slightly over a year now.

Of course, now I have probably jinxed it. :lol: :lol: :lol:

Had a JJ 6L6GC fail after a couple of years.

In that same time I have had a GT 12AX7 and NOS JAN Philips 5751 fail.

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Post subject: Re: Early JJ output tube failure.
Posted: Sat Mar 09, 2013 10:25 pm
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I have older Sov-Tek GZ34's in a couple of different vintage amps -- thus far they've been grenade-proof.

Sounds like JJ has had a bad run of bottles recently. It happens. No way to predict such premature failures. I've never been a big fan -- I'll only install them if they're a client's preference.

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Post subject: Re: Early JJ output tube failure.
Posted: Sat Mar 09, 2013 10:33 pm
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I'll be running JJ E34Ls in my Trainwreck clone. Should be interesting. :D

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Post subject: Re: Early JJ output tube failure.
Posted: Sun Mar 10, 2013 7:18 pm
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Bill, I must be lucky. I have A pair of 6V6 and EL84's in my Egnater for over two years with no problems at all. I also have a JAN Phillips NOS 5751 in V1 that I put in when the amp was a couple weeks old. My Egnater gets gigged and rehearsed pretty hard. I have a set of JJ's in my 5e3 clone with a GZ34 rectifier. We'll see how that works out. I've been running that amp pretty hard just to check it for reliability and durability before I gig it. So far so good.
My oldest are in the Egnater. I got the JJ's from Eurotubes. The GT branded JJ'S only lasted a couple weeks before thet started rattling. I never had any tubes rattle in a amp head before. I never had any luck with GT's,

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Post subject: Re: Early JJ output tube failure.
Posted: Sun Mar 10, 2013 8:38 pm
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63supro wrote:
Bill, I must be lucky. I have A pair of 6V6 and EL84's in my Egnater for over two years with no problems at all. I also have a JAN Phillips NOS 5751 in V1 that I put in when the amp was a couple weeks old. My Egnater gets gigged and rehearsed pretty hard. I have a set of JJ's in my 5e3 clone with a GZ34 rectifier. We'll see how that works out. I've been running that amp pretty hard just to check it for reliability and durability before I gig it. So far so good.
My oldest are in the Egnater. I got the JJ's from Eurotubes. The GT branded JJ'S only lasted a couple weeks before thet started rattling. I never had any tubes rattle in a amp head before. I never had any luck with GT's,


I buy all my JJs from Eurotubes and Eurotubes only. They do a 24 hour burn in for power tubes. Service is fantastic.

http://www.eurotubes.com/eurotubes-test ... rranty.htm

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Post subject: Re: Early JJ output tube failure.
Posted: Fri Mar 15, 2013 9:47 am
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I've had similar problems with JJ tubes. Recently, I repaired a 1964 Fender Concert amp which had a pair of GT 6l6GE's. They were old so I installed a pair of JJ 6L6GC's and biased them. The sound was lifeless and dull. I decided to swap power tubes. The GT 6l6GE's sounded very good as did TungSol 6L6 STR's. I also installed a set of Ruby Chinese 6L6's. All of them sounded much better than the JJ's. I've had JJ preamp tubes go south right out of the box. This is just my experience. I know many folks like them.


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Post subject: Re: Early JJ output tube failure.
Posted: Fri Mar 15, 2013 10:38 am
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+1 on the T-S STR's.

I've only recently become aware of them but I bought a matched quartet for use in a Bassman 135 and they seem to be more that up to the task thus far.

Arjay

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Post subject: Re: Early JJ output tube failure.
Posted: Fri Mar 15, 2013 2:46 pm
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I was very happy with the 6L6GC STR Tung-Sol RI's
That is what i ended up with in the 67 Bassman and they sound very good !
The short bottle TAD's were also very good.

After looking around the net for people who had reviewed the current crop of EL34's there looks to be about the same opinion there too.

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Post subject: Re: Early JJ output tube failure.
Posted: Mon Mar 18, 2013 8:58 am
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It's good that there are some tough Russian tubes still being made. These 6L6GC look a lot like the black plate, mil spec Soviet-era tubes. Some of the best made types of their era.


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Post subject: Re: Early JJ output tube failure.
Posted: Thu Apr 18, 2013 1:33 pm
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I have a pair of JJEL34L's in a Silver Jubilee kranking for almost a yearand sound as good as TS or GL's. Bought them from a music store-factory matched-2 ma apart.


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Post subject: Re: Early JJ output tube failure.
Posted: Mon Apr 22, 2013 11:55 am
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I'm looking for a fresh set of EL34's for my taynor, the TS sound interesting, I've read that they have a bit of 6L6GC sound to them.

Might be just what the doctor ordered for that circuit !
It has a pair of no name el34's in it now that look very old and so a nice fresh pair may liven up an already sweet sounding amp 8)

Wish I could find a pair of 40/40uf filter caps for it (firecracker style).

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VHT Special 6 Ultra combo

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