JJ 6V6s sturdiness

[txstrat]

Hi all,

recently one of my builds developed a hum I coudn't explain to myself.
I opened the amp to poke around inside for troubleshooting.
First thing I did was measuring the plates voltage (390 vdc) and the bias current - oooops that was 45ma (1 ohms resistor) per tube.
Set the bias to 28ma and the amp's been quiet again.

I would have thought the tubes might redplate with this high a current but not the slightest sign. Great stuff from JJ.

[bob p]

my experience has always been that JJ made very robust 6V6. i don't understand why some people like to bash them.

[jrfrond]

my experience has always been that JJ made very robust 6V6. i don't understand why some people like to bash them.

OK, I'll bite.

I've replaced more bad JJ 6V6's than any other tube. I wouldn't touch them with a barge-pole!

[Robert M. Martinelli]

Hi all,
I can witness all the above statements of yours to be true.

How is this possible? How can a certain manufacturer produce "great" and "bad" tubes at the same time?

Well, I think the problem is that QC seems to have gotten worse at JJ.

I have been using their tubes for a number of years ( remember when their trade name was still "TESLA" ? ), and I can say that the "good ones" are very good value for the money, but, lately, I have been dealing with some "bad right out of the box" JJ tubes ( one ECC83S and a couple of EL84s ) and this means that QC at the factory is not that good anymore.

FWIW this seems to have become a problem with other stuff as well ( e.g. cars, mobile phones.....you name it... ) - Looks like manufacturers tend to accept the risk of putting a certain number of "bad" specimens on the market "delegating" QC to customers.

This might save them some money, but in the end it sure as hell doesn't any good to their reputation IMHO. It's not OK to have customers having to rely on their luck ( especially the unlucky ones like me ).

JM2CW

Cheers

Bob

[tubeswell]

I've never had any bad JJ 6V6s or 6L6GC or GZ34s yet. (I've never run any of their other tubes in my amps)

[Steve Conner]

Tesla were a big manufacturer of tubes and other radio electronics in what was then Czechoslovakia. They were in business since the 60s if not before.

JJ started in the 90s, around the time that the country split into Slovakia and the Czech Republic, and may have inherited some tooling from the old Tesla plant, or even the whole plant. I'm not sure. But they're not the same company by any means. There's a lot more to vacuum tube making than just having the right machinery.

Mass production is full of QC problems like these, and the selection effect of the Internet makes them look bigger than they are. For instance, check out a site like appledefects.com: if you only read this site, you would think Apple made complete junk. But there's no site for the silent majority of happy Apple users to blog about how their kit isn't breaking down, and they wouldn't use it if there was. No news is good news and all that.

[Robert M. Martinelli]

Tesla were a big manufacturer of tubes and other radio electronics in what was then Czechoslovakia. They were in business since the 60s if not before.

JJ started in the 90s, around the time that the country split into Slovakia and the Czech Republic, and may have inherited some tooling from the old Tesla plant, or even the whole plant. I'm not sure. But they're not the same company by any means.

Hi Steve!
AFAIK JJ is the trade name the ( previously "state owned" ) TESLA company took after going private, back in 1993 ( if memory serves me well ), so they inherited the tooling/plants, but, as you said, there's more in vacuum tubes manufacturing than owning the right machinery - and we don't know if, after going private, the new owners kept the old ( but knowledgeable and experienced ) staff or not...

Anyway, since the process we're talking about is a fairly complicated one, QC should play a major role there IMHO.

As I said, JJ tubes are good value for the money, I just wanted to point out that something in their QC procedures/criteria must have changed ( for the worse ) because I've never had problems with their tubes before.

Cheers

Bob

[txstrat]

I didn't think about this thread going the way it has when I started it. I was just thinking that the tubes in my amp are quite rugged.
I understand what everybody's saying and to be honest, in the bunch of tubes I bought for this amp were two JJ 6V6s and five JJ ECC83s (one Tung Sol 12AX7 to make it complete) of which one went bad after a month or so. I returned it with no problems so I haven' spent a lot of thought's about it afterwards. But now I know better... or not.
Thanks for sharing your opinions.

[BackwardsBoB]

A repair guy might make a better judge than me, but I've bought alot of JJ's tubes for personal use. I do note that most of the major manufacturers aren't using JJ's, so many of the JJ's tubes in the field went into amps that had already had a tube failure.

I've ordered a few batches of 6L6s, and did get one that developed a vacuum leak, probably during shipping. I've got 6V6s in my 455V Carvin XT112, and they are running well, with lots of hours on them. I have a Carvin X30 with plate voltage over 470V, and got two tube failures with 6V6s in two pairs (God intended both amps to be run with 6L6s). Both seemed like screen shorts. Investigating further, I found that for two years, Carvin decided to make X30s and X60s without screen resistors (but the fuse on the AC works really well...). I also suspect a grid voltage surge coming out of standby, since a power-cycle seemed to induced failure in both cases. It's hard to blame the tubes until I drop the B+ a bit and check for the surge.

I think the NOS 6V6s have a bit more personality than the JJ's (this seems true of most of the JJ's lineup), but I searched the web before I installed the JJ's, and found plenty of evidence that they could take the higher voltages present in sockets designed for 6L6s.

I like many things about Carvin's X30 and X60 combos, and I think the sound of my Fender Deluxe Reverb Re-issue is obtainable (I'd love to sell it to buy something nice, but it does have that tone...), and I've got a new, better-matched output transformer, some power resistors, some zeners, a quad of used Red Banks 5992s, some 5W 1K screen resistors and a Jensen P12N ready for my next try.

I believe that Eurotubes' fast shipping, great support and cool t-shirts add to the value of their JJ's line. Still, I meet more and more of my tube needs with used vintage tubes that I purchase and re-test. You can get a used vintage RCA, supposedly tested, for less than the price of the new wanna-bes, and swapping them in and out is a pleasant diversion.

[jrfrond]

Having slammed JJ (and I do think they suck overall), there are sporadic QC issues with ALL tubes. In the old days, I remember having issues with Sylvania 6L6's, so this is not a new occurrence, just more frequent. I'd have to say that the stuff coming from the Reflector factory (Sovtek, E-H, Tung-Sol, Mullard) has been ultra-reliable and sounds excellent, for our shop anyway. Every once in awhile I get a lemon, no biggie. I do have to say that the new Tung-Sol tube have been great and sound amazing, especially for the price.

[jbltwin1]

jj 6V6's

This is ALWAYS interesting to hear other opinions. Admittedly, I don't go through the numbers that some of you guys do but I STILL swear that WHERE you get your JJ's seems to determine how well they work. I'm not trying to pump up anybody so I won't even say where mine come from but I seem to get great results out of JJ's. I won't put anything but JJ E34L's in musicman amps, and use the hell out of JJ 6L6's. 6V6's get a good grade here also. I've abused the hell out of some 6V6's just to see what they would take and they held up. I've always wondered if it was the shipping that damaged them. HMMMMMMM? I'm just sayin'. On the other side, I wouldn;t put Glue Tubes in a radio. The track record that I have with them sucks, yet I know people that swear to them(I swear AT them). Sovteks hold up, sound funky. I admire Johns opinions so I would listen but MY pick for the above three is JJ's and Winged C's are also good in 6L6's and EL34's but they have REALLY gone up. EL84's in JJ are also a winner here. You pay's your money and you takes tour choice! Mike

[jrfrond]

This is ALWAYS interesting to hear other opinions. Admittedly, I don't go through the numbers that some of you guys do but I STILL swear that WHERE you get your JJ's seems to determine how well they work. I'm not trying to pump up anybody so I won't even say where mine come from but I seem to get great results out of JJ's. I won't put anything but JJ E34L's in musicman amps, and use the hell out of JJ 6L6's. 6V6's get a good grade here also. I've abused the hell out of some 6V6's just to see what they would take and they held up. I've always wondered if it was the shipping that damaged them. HMMMMMMM? I'm just sayin'. On the other side, I wouldn;t put Glue Tubes in a radio. The track record that I have with them sucks, yet I know people that swear to them(I swear AT them). Sovteks hold up, sound funky. I admire Johns opinions so I would listen but MY pick for the above three is JJ's and Winged C's are also good in 6L6's and EL34's but they have REALLY gone up. EL84's in JJ are also a winner here. You pay's your money and you takes tour choice! Mike

At first I thought you were crazy, but I use shitloads of tubes from New Sensor, who is local to us here in NYC, and rarely have problems, yet I have heard about people across the country with issues, so perhaps at least SOME issues with tubes is that the new stuff doesn't ship well. Still, they ALL have to make it here from the Eastern Bloc, but then there is UPS to contend with.

Do don't have to divulge your source for JJ's (I'm not purchasing them anyway), but are they at least in the same general geographical area as you are?

I stopped using Winged-C/Svetlana 6L6's, which I love, because I was getting to many bad ones, and I mean really bad, with arcing and all that, and it didn't happen until distribution went to CE Distribution after their battle with New Sensor. It just so happens that CE is in AZ, a much farther trip than NYC.

So yes, this theory, to me, DOES hold some water.

[jbltwin1]

jj's

Honestly, I didn't say where I get mine because SOME people seem to have a woody for him but Eurotubes is where they come from when I go JJ. Like I said, some peoplehave great luck with all different kinds of tubes. I remember Vintage Jon loved Ruby tubes and I had nothing but bad luck with them. Glue Tubes, junk to me but other people love them. THAT'S why I just kind of figured that the one variable other than piss poor manufacturing is the bouncing that they take. UPS DOES stand for underhanded power slam you know. I've always respected John's opinions as he's out there on the front lines doing it every freaking day whereas some of us do it part time. By the way, I'm in the midwest but Eurotubes ships from some gawd forsaken place in oregon. Go figure. Maybe that pisses all over MY theory!

[Tele-Cat]

I like JJs. I have them in all my amps in some form. An ECC803s all my amps (5F1, 5E3, 5F4), also 6V6s in my champ and Deluxe. I have SED 6L6s in my Super. All have performed flawlessly.

I don't go through much in the way of numbers but my luck with JJ has been good, though a friend had a bad 6V6 right out of the box.

OTOH, I've had very bad luck with anything Sovtek. Leaky, microphonic, loose pins, you name it.

[rockon1]

Perhaps the QC on some of the JJ's isnt up to snuff but once properly screened by a good tube dealer they are the stoutest 6V6 made-ever. Ive ran them in my old Supersonic at 470 volts and now in my Rivera Chubster at 430+ volts for quite a while. In fact they are rated at 500 plate/450 on the screens. I like to call them 6VL6's! lol! Bob