I was ready to buy a matched quad of JJ 6L6GC power tubes when I noticed a lot of dealers selling burned in JJ's for 5 dollars more. Seems like a good deal but I figured I'd email JJ to see what they thought about it. They said they already burn them in at the factory so there's no need to pay extra. I emailed some dealers to ask what their burn in is process but never received any replies. Any thoughts on this would be appreciated.
Any maker worth their salt burns their tubes in. It's a necessary part of the manufacturing process. And I strongly suspect some do a better job then others. The better dealers will also process output tubes with a further burn in. Perhaps not to simply use it as an advertizing or sales advantage, but to assure themselves that the tubes they sell will hold up. Having to replace tubes that fail prematurely is a drag on business. But for either reason, it's a win-win situation.
Thanks HollowState, I think the dealer I'm buying them from is one of the good ones. I've always had good luck with JJ 12ax7's and from what I've read about the 6L6's they seem to have a good track record as of lately so, I think I'll put the 5 dollars towards some more 12ax7's.
I don't believe manufacturers "burn in" all tubes on a scale that demand requires........too much time sucked up on the soak rack and alot of electric....all overhead costs everyone is longing to cut back......so perhaps 1 out 10 and do the stat analysis.
When asking a vender about "burn in"; mention the approx operating conditions of tube(s)....also mention to "tap test". There is a proper impact gforce for this.. I found it's worth it esp B9A (microphony) and Int oct power types...where premature failure shows up pretty quickly.
Some will remember the earliest 1990 Chinese KT88 and other Sino clones produced some of the brilliant fireworks when tapped, many fell into the trap of putting these tubes directly into amps which were inbuilt within the loudspeaker cabinets, the resonance doing a perfect destruction of the tubes plus alot of circuit damage.
richy
When asking a vender about "burn in"; mention the approx operating conditions of tube(s)....also mention to "tap test". There is a proper impact gforce for this.. I found it's worth it esp B9A (microphony) and Int oct power types...where premature failure shows up pretty quickly.
Some will remember the earliest 1990 Chinese KT88 and other Sino clones produced some of the brilliant fireworks when tapped, many fell into the trap of putting these tubes directly into amps which were inbuilt within the loudspeaker cabinets, the resonance doing a perfect destruction of the tubes plus alot of circuit damage.
richy
I always purchase power tubes matched and burned in - the matching having occurred after 24hrs of burn in minimum. This process also IMHO reduces problems with infant mortality, and with reputable vendors usually results in tubes that remain reasonably well matched over their life time. (Not always the case)
The manufacturer being discussed has been much maligned lately for poor quality product wrt octal based power tubes and poor QC practices in general.. I'd be particularly leery purchasing power tubes of any brand without further burn in and testing by the seller. Most of the higher volume producers appear to have variable quality over time. I've had bad experiences with nearly every manufacturer currently making tubes. Caveat Emptor!
YMMV, and all above is just my opinion - speaking only for myself.
The manufacturer being discussed has been much maligned lately for poor quality product wrt octal based power tubes and poor QC practices in general.. I'd be particularly leery purchasing power tubes of any brand without further burn in and testing by the seller. Most of the higher volume producers appear to have variable quality over time. I've had bad experiences with nearly every manufacturer currently making tubes. Caveat Emptor!
YMMV, and all above is just my opinion - speaking only for myself.
I bought a matched quad of JJ 6CA7's in 2010, they are fine. Great, since the alternate source pays taxes to an oligarchy. Since the boxes were marked with a number, perhaps the manufacturer did the matching.
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I suppose another 5 dollars is worth it as long as the dealer burns them in further. I didn't find out how long a period JJ burns them in but they claim they match them for GM and Plate current. I have a set of 8 JJ EL84's in my Peavey 50/50 for over a year and they are ok and sound great. I'll have to contact the dealer and see how much longer they burn them in for.
I am VERY reluctant to deal with JJ tubes at all. There are a few that are okay - EL84, the 12DW7/ECC832, and a few others - but the octal power and rectifier tubes I won't even stock. Too many rejects, I simply can't afford to handle tubes with such high reject rates.
Regarding vendors burning in tubes - infant mortality is the #1 problem with tubes, so any rational steps taken to minimize it are worth doing. I don't charge any extra, but that's me - what others do is up to them.
I think Kevin's post above is pretty much right on target.
Perhaps some TAD 6L6GC-STR's are the way to go. I read a review stating the similarity to the JJ's tone but one step better and worth the extra cost. I just want something with nice lows without breaking the bank. I tried Winged C's in the amp and they sounded thin. I thought the JJ's were the way to go but maybe the TAD's would be better.
I've had problems with all brands. So I can't recommend any that stand out when it comes to failures. Now I buy from a few of the larger sellers and keep track of tube rating in case 1 blows out. I also think UPS damages more tubes than usual. It's ashame the quality can vary so much. It seems if the tube last the first month, they're going to be OK.
Of course you've had some trouble with all brands. That has always been the case, RCAs failed, Mullards, Sylvanias, all of them. As has been posted, infant mortality is and always has been an issue.
It's a question of degree. A few failures is to be expected from a hand assembled device, regardless of brand. But 50% (as one of my JJ batches exhibited) failures is a whole different story.
Was that just one batch or many over an extended period of time, and was it recently or back around 2008-2009 because it seems like that time period shows most posted failures. I'm curious to know if their qc standards have improved over the years. Maybe Pooty , as W used to call him, had something to do with it.
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