JJ 6L6GCs... WTF?

[Leo_Gnardo]

Sorry to hear that Bruce. Makes me wonder about what to order for my next batch.

Well folks I had a look at Eurotubes' website during the pre dawn hours today. I must admit they're pretty brave to have a button that links to this:

Why We Prefer JJ Tubes (A letter from Eurotubes to TGP) [Archive] - The Gear Page

Builders & Retailers Forum on The Gear Page kicks JJ/Eurotubes every which way, from praise to slagging. And if our friend bob p reads the TGP thread, well buddy you better have a well chilled giant economy size icebag strapped to your head because you will just about blow your top. Only a couple comments into the thread and Euro's 'preferential treatment' starts to get a mention. (One correspondent even mentions "illegal" never mind unethical.) Mentioned quite a few times - good JJ's can be had from Euro, and other suppliers not so much. Note I never said unethical or illegal on this forum or anywhere, and if one distro gets the "cream of the crop" then why not buy from them? I don't see anything wrong with that at all. That it's taking us so long to figure it out... well at least in mid 2008 the TGP folks had it mostly figured out. And from a read of Bob 'Eurotubes' Pletka "Trip to Slovakia" story, OK he's NOT a relative of JJ's boss. Giving some "hometown advantage" to a fellow countryman, it's common and I don't have any problem with it - whether it's Bratislava Bronx Brisbane Brunei Bangalore or wherever. It's human nature. People will do that & you can't stop 'em. Heck, unless it's insider stock trading, there's no penalty and "the law" AFAIK doesn't demand "fair and balanced" trade amongst private companies. If I'm wrong, set me straight.

Bottom line Dude & others, if you like JJ, looks like you oughta get 'em from Eurotubes. Worth a try anyway. I'm going to try that route myself soon come. Them what don't like it, put it in your pipe & smoke it & have a nice day.

[bob p]

I asked for facts to back up your accusations that Eurotubes had a direct connection with JJ and you directed me to a 7-page flame war on the gear page. WTF?

I'm not going to waste my time reading 7 pages of bullshit on the gear page. I'm really surprised that anyone here would be willing to parrot such libelous garbage as if it were fact.

[soundmasterg]

For anyone who is curious, I get a lot of stuff from CE and like someone above noted, I have to have them on my good side as a result. The last couple years if I want to use JJ in an amp, I go to Eurotubes for the most part because they are local to me. I can avoid shipping costs, and usually when dealing local and face to face, you get better service generally. The guys at Eurotubes are decent enough and while some of them may not know as much as they seem to insinuate about tubes and amps, they do have some knowledge. They tend to put JJ at the top and disparage other makes sometimes...but given that they only sell JJ, that is sort of expected. They do have some very nice tube testers and matchers that check for noise in addition to the other usual things. They test every tube..I don't know for how long or any of that, but given that I haven't gotten any bad ones from them and I have from CE and others, I think they probably do a better job of weeding out the chaff. That said, I don't go through tubes like Bruce @ Mission Amps for example, so if says he is having a problem with JJ's then perhaps it might be the case. Only way to know is for him to try Eurotubes instead of CE and see if the problems repeat. There are a lot of haters out there as far as Eurotubes is concerned....and any business in business long enough will have people who like them and people who don't. I get good service and good products from them when I have gone in the past, so I will continue to use them as a vendor in the future. If CE gets their act together on testing, then I may change up in the future regarding JJ tubes because they do have a cheaper price, and since I order a lot of stuff from them anyway, adding some tubes into a shipment isn't a big deal.

Greg

[Enzo]

I have been using the Ruby EL34B since they came out, and so far have not gotten a bad one. They seem to be sturdy and reliable to me. SOund like EL34s to me. For that matter the Ruby 6L6GCMSTR (or whatever order the letters are in) have also been very rugged and reliable for me, I have never gotten a bad one. I generally buy from CE. I only buy matched tubes, so they have all been burned in at least enough to match. That alone sorts out some bad ones before I get them.

[bob p]

Matching -- now there is an important point. When you pay extra for a matched tube, you know that somebody bothered to test the tube, at least for a short time. That tends to weed out at least some of the bad ones. If Euro tests every tube, then that's a good thing. Does CE test every tube? I don't know for sure, but I doubt it. I'm guessing that they don't.

I've never bought from Euro, so I don't know if they have an upcharge for matching. I do buy from CE, and I've always paid extra for matching, and I've never received a bad set.

Are you guys who are receiving bad tubes paying for matched tubes or not?

What's interesting about the matched sets is that every time I've bought a matched set of JJ tubes, regardless of the supplier, the matching numbers have been handwritten on small circular labels affixed to the boxes and the boxes for the matched set have been taped together. The handwriting on the boxes contains two numbers. For example, I have a set of EL84 on my desk and the numbers are "26.8/7.12", and for a pair of 6L6GC the numbers are "13/2.4". I haven't de-coded what the numbers mean -- I know it should be something obvious like gm, Rp or mu, but I just haven't applied myself to figure it out what the 2 numbers represent. Anyone?

What I find most interesting is that the handwriting on the stickers looks very Central European to me. I don't know if any of you have experience reading handwriting from Central Europe, but the matching numbers on the boxes I have received from two different suppliers looks decidedly Central European to me.

Recognizing that characteristic of the handwriting, I've always wondered if the numbers on the boxes are matching numbers that are provided by the factory. If that's the case, then consider this bit of speculation: Maybe the factory sells two different tiers of tubes to their customers -- matched at the factory and unmatched. If that's the case, then maybe you don't want to buy the unmatched tubes, as some method of selection might be taking place at the factory.

It's encouraging to hear that Euro tests every tube. IMO that's a form of value-added-resale that's worth paying for.

[Leo_Gnardo]

I have a set of EL84 on my desk and the numbers are "26.8/7.12", and for a pair of 6L6GC the numbers are "13/2.4". I haven't de-coded what the numbers mean -- I know it should be something obvious like gm, Rp or mu, but I just haven't applied myself to figure it out what the 2 numbers represent. Anyone?

What I find most interesting is that the handwriting on the stickers looks very Central European to me. I don't know if any of you have experience reading handwriting from Central Europe, but the matching numbers on the boxes I have received from two different suppliers looks decidedly Central European to me.

Plate current and gain, in whatever "standard" test rig they're using. Possibly something custom made that hopefully puts "real world" voltages on the tube elements.

Magic/Ruby also Tube Amp Doctor use machine printed labels and the gain is expressed in a number that's 1000x the CE number. Perhaps one uses the MKS system and the other CGS. We can be darn sure the gain of a power tube isn't 3125 for instance.

Interesting to note the handwritten numbers. I expect what you're seeing is a 1 that looks like a 7, a 7 with a line thru the middle, a strange looking 4 and maybe a 9 with a hooked "tail" sort of like a "g". I had a look on 2 tube sets I got from CE that aren't JJ. They have yellow round stickers about an inch across, with a green line across the middle. And by coincidence, none of the telltale numbers I mentioned.

[Tom Phillips]

...Magic/Ruby also Tube Amp Doctor use machine printed labels and the gain is expressed in a number that's 1000x the CE number. Perhaps one uses the MKS system and the other CGS. We can be darn sure the gain of a power tube isn't 3125 for instance...

I believe that 3125 number is their measured transconductance value. Don't know how they have calibrated their equipment but the number is in the ballpark for a power tube's transconductance in µmhos.

[daz]

In my work we have many amps that are retubed fairly often, and we buy JJ's from eurotubes, last batch being bought maybe 3 months ago. In several years i literally cannot remember one bad 6L6. In that time we've installed i'd say 30 duets of 6L6 JJ's. In fact, I can't recall any JJ being bad out of the box. maybe it's the supplier more than the tube? eurotubes i think weeds out any bad ones.

[Leo_Gnardo]

I believe that 3125 number is their measured transconductance value. Don't know how they have calibrated their equipment but the number is in the ballpark for a power tube's transconductance in µmhos.

DOH! How could I have not realized... Big Clue: "Tc" is the label designation. OK now I have the dunce cap parked atop my bald spot. Do you think it stands for Transconductance. Very well could be.

Maybe Stan could confirm this - he helped Magic/Ruby with their test gear. QSL de KM6SZ, QSL de KM6SZ .....

[Chuck H]

QSL de KM6SZ, QSL de KM6SZ .....

Careful with that. We'll get a two page sermon!

Just poking at Stan. He's actually one of very few members here that can write an essay sized post that I'll actually take the time to read!

[Leo_Gnardo]

Careful with that. We'll get a two page sermon! Just poking at Stan. He's actually one of very few members here that can write an essay sized post that I'll actually take the time to read!

Stan's sermons never put me to sleep. Looking forward to the next one, short or long.

QSL de KM6SZ - if you're not dancing with those beautiful blondes let's hear from ya! No rush really, take your time.

[Enzo]

As far as I know Bob does test each tube. And as for bulk tube sellers, I expect them not to unless they are graded. If I buy 12AX7s from Ruby, they have some extra price selected ones with lower noise or microphonics. Worth the price for high gain stages.

The matching numbers all pertain to the test setup and are not real world useful figures. So the plate current reading of 29 on the tube I am holding means they got 29 on the meter of their test rig under the conditions of test. Some people actually expect to plug the tube into their amp and measure 29ma. SO the two numbers on a label are typically transconductance and plate current. But they are only from the test system. If the test system gives same numbers, we can generally assume they will behave similarly in the real world. And even transconductance meters can be read different ways. One team might read 3500, while another company logs it as 3.5. Hell, I even do that. Sometimes I write 1.5k resistor and other times a write 1500 ohm resistor.


Factories do sell select and ungraded tubes. You can buy either way. Bulk ungraded tubes are a lot cheaper, but you eat the bad ones yourself. A friend of mine once worked at an audio manufacturer. They made preamps, and wanted balanced 12AX7s. They bought the tubes in bulk, and the rejects were either discarded or given to employees. I was the lucky recipient of a surprise box of 100 12AX7 tubes. And I surely do not care if they are balanced before sticking them into a Fender amp. Point being, that company found it cheaper to grade th bulk tubes themselves and accept the reject rate.

I am looking at a pair of JJ 6V6 from CE, each box has the round yellow dot with a line across the middle 24 over 2.8. The handwriting does look crude, one of the 2.8s has the 8 almost sideways. It could be east European, but to me it looks like someone wrote it in the fly, like they reached over to it. The JJ boxes are preprinted JJ boxes. Next to them is a quad of Sovtek EL84, also from CE. Same yellow dots with a line, and the numbers 23 over 5.3. Yellow dots all look alike to me, so they could be from the same place or they could be from opposites sides of the ocean. And the handwriting is not the same. The box is plain white, but for a preprinted end flap that says "SOVT EL84". Just a guess, but I bet the JJ boxes came from JJ, and I bet the white boxes are CE supplied. All the Ruby tubes I buy from CE come in Ruby preprinted boxes and each box has the same preprinted RUby matching label as is on the tube base. SO their system prints out more than one label per tube. The RUby label has printed on it the tube type, the PC and TC numbers as well as a tube number - "IMG Matched #" I don't know if that is a batch or what exactly. I note on a quad of some larger tubes, I see IMG# of 12,13,14,15 on the four tubes.

In my experience with CE, if I got a bad tube in a quad, I could call them up, and they would send me just the one replacement, but it had the same numbers for PC and TC.

[Bruce / Mission Amps]

The JJ6L6s I get from CE Dist are always purchased in matched quads... as I think I previously stated.
In any given month I might buy 6 to 12 sets of quads.
The idle current specs, as measured in the subject amplifiers after power testing for a bit, are always within 2ma or 3ma of each other.
I'm quite satisfied with that.

The problems I have been running into is that the JJ6L6 tubes from CE Dist are almost always unusable because they very quickly become mechanically noisy, rattling, ringing, buzzing and singing away.
It is not a loud noise that comes out of the speaker so much, although those same tubes do have microphonics you can CLEARLY hear right through the power amp stage if you lightly tap the tube, which becomes much worse as time progresses.....but the tubes make their own noise that is quite discerning.
It sounds like all the mica and support structures inside the glass envelope are loose, jangling the glass envelope and the parts are excited in "sympathy" with what ever low to mid tones are going through them.
They radiate their own noise and it sounds like there is something wrong with the amp.
The bad tubes that do rattle badly fail within half the time or less of tubes that do not do this.
I think that is a major defective... CE Dist sells them this way and tells me they do not warranty microphone tubes as they do not consider that a defect.
So, bottom line, I buy many thousands of dollars worth of tubes every year and CE just doesn't get my power tube money anymore.
NONE of the currently purchased Sovtek 6L6WXTs I have been using exhibited any of this damn noise and although not my first choice in tubes, they still sound good and I can ship the amps out with out worrying about a warranty issue on power tubes due to a noise complaint.
As mentioned by a previous participant, I think I will try buying a JJ6L6GC set from Eurotubes at retail and see if they are better in this regard.
If yes, then I will continue to hound CE Dist.

[bob p]

Sorry, Bruce, if I'm asking questions that you've previously answered, but as time drags on I forget some of the things that have been said.

I'm sad to hear that you're getting low quality matched JJ 6L6GC from CE. that has me worrying about buying a matched sextet from them for my SuperTwin. I do like the low cost at CE, and the thought of buying a sextet at retail isn't all that appealing to me. Does Euro even have a wholesale channel?

I'd be interested in hearing if you have better luck with buying the JJ 6L6GC from a different provider. By your last post, it seems like you've voted with your feet and you're buying your Sovteks elsewhere. Am I correct in assuming that you are getting them directly from NewSensor? I haven't bought from them in so long that it looks like my account has rolled off of the system, so I can't even compare the jobber prices.

[Bruce / Mission Amps]

Sorry, Bruce, if I'm asking questions that you've previously answered, but as time drags on I forget some of the things that have been said.

I'm sad to hear that you're getting low quality matched JJ 6L6GC from CE. that has me worrying about buying a matched sextet from them for my SuperTwin. I do like the low cost at CE, and the thought of buying a sextet at retail isn't all that appealing to me. Does Euro even have a wholesale channel?

I'd be interested in hearing if you have better luck with buying the JJ 6L6GC from a different provider. By your last post, it seems like you've voted with your feet and you're buying your Sovteks elsewhere. Am I correct in assuming that you are getting them directly from NewSensor? I haven't bought from them in so long that it looks like my account has rolled off of the system, so I can't even compare the jobber prices.

Yes, I get the 6L6WXTs from NSC in Long Island at a better price anyhow.
FWIW:
I just tested at least a couple dozen (1 1/2 hours of wasted bench time) from a batch of JJ6V6s for my new 15 watt harp amp, the Delta Sonic 15.... and NONE of them are noisy or bad.... it appears to be the JJ6L6s.
I had been using Tung-Sol 5881s in those Chicago harp amps but I started liking the JJ6LGCs better in my higher powered harp amps... but this JJ tube noise made it impossible to continue using them and ended up wasted hundreds of dollars.