JJs

[Chickenwings]

AAAAAAGH!
got home from work and flipped the amp on to get the most ungodly noise! i thought the amp was melting down!
The power tubes were glowing and crackling and it was like a science experiment gone wrong.
Then i noticed - even thru the tube shield than there was a bright purple glow coming from v3. Like a purple light globe!
So - new (old) 12at7 gets popped in and all is okay in the world again.
So i guess a lot of the problems over the last few days were cause by this tube heading towards meltdown.
Fwiw - the one that failed was (again) a JJ. Dont know if i just got a bad batch or what. I got a bunch of jj ax7s and at7s recently and have had them act up in two different amps now.
So heres a list of stuff that i have had to deal with with 2 amps in the last week:

1. weird crackling/distortion from my princeton - jjs in v1 and 2.- solved with tung sols and a NOS sylvania. Just looking at the things - jjs glow much more than eh or tungsol, or even the old stuff i have lying around like old phillips and Haltrons etc.

2. PI meltdown in the twin - ok to be fair i was using a jj 12ax7 instead of an AT7, but yeah - jj nonetheless which crapped out. I am now using a JJ at7 as at7s are whats designed to go there, but im not feeling confident because:

3. V3 total AT7 chernobyl meltdown.....again a jj . Replaced with an ancient phillips with no issues.

4. Weird noises from the vibrato/trem....jjs. Fixed by replacing with EH.

5. My old musicman amp (which i sold to my jazz duo partner) has developed a buzz in the reverb. It has got a jj in the PI slot....im gonna swap it out and get back to you guys and see. I used to have al old mesa in that slot, and never had an issue, but i put in a brand new jj because i wanted his amp to be all freshly tubed and reliable. We will see on this one....

SO....what a bummer! i have jjs in the power sections of all of my amps and found them to be great and reliable.
but yeah as far as preamp tubes go, i have had 3 crap out this week alone - and all were new (less than 2 weeks use) jjs - in 2 different amps. Also, they have been shown up as inferior in normal operation by other tubes of many brands and ages. Im bummed because i like the tone of jjs, but especially because i always thought they were the most reliable. This has happened with both ax7s and at7s being used in the correct amp slots for the correct job...the only exception was using an ax7 in the PI slot....so ill write that one off, but the other failures/poor performance were normal operation.
So yeah - maybe i play old amps and maybe there are other issues causing this.....but even when everything is running fine, tungsols and EHs run with less noise and at least visually seem to run cooler. Good tone or not, i have lost confidence in jj pres.
I have 3 of them in my marshall now (which runs pretty hot in the preamp) and we will see how long they survive.
This is of course one person's experience.....anyone else care to chime in about any particular brands reliablility and experiences?

 

[JeffB]

Re: JJs

I never had an issue with JJ 12ax7 reliability because they did not last long in my amps I put them in. Did not like the tone at all.

People rag on them, but I've never had a Groove Tube branded tube ever die or get weird. They may not always sound the best, and they may be expensive for what they are, but they do seem to last a helluva long time. I had a pair of El34s (cannot recall the re-brand) and set of their 12ax7 Sovtek re-brands in my 1987 for about 10 years. Always worked and had good tone. I didn't play every day for hours on end, but I put a huge amount of hours on those tubes- full blast.

 

[misterwhizzy]

Re: JJs

Interesting. I've had two Tung-Sols get noisy in V2. I recently put a JJ in there, and it solved some of my problems. In fact, despite all my hatred of JJ pres, two out of my three preamp tubes are JJs. (One is because it's the only 12AU7 in new production, but that's beside the point.)

It sounds to me like all your JJs are failing because all you use is JJs.

 

[IanBallard]

Re: JJs

Probably a bad batch. They are pretty renowned for reliability and why many people use them, in spite of their somewhat dark-ish tone. They shine in bright plexis and are based on old ECC83 designs like the old ones.

I'm considering a JJ ECC82 for my PI to get rid of some of the buzziness when the gain is cranked and give me better clean headroom. Hopefully I get one from a better batch.

 

[Chickenwings]

Re: JJs

Whizzy:
heheh...nah i use tung sols, EH and jjs - both preamp and poweramp slots. I also have an assortment of old tubes that i have replaced with one or all of the above. Ive also used sovteks a fair bit, but only if they are there already. I just like the tone of jjs, so i usually have them in the first preamp slot.
I will admit that i have had other brands of tubes die on me, im juts kinda frustrated cos its not only the fact that 3 have died this week, but also that under normal operation i have found other tubes to work better (less noise, less heat etc). until i bought this most recent set of 10 jj tubes ive never noticed any issues outside of "every now and again".

Ian:
yeah maybe a bad batch....i bought a whole bunch at once, but its odd that im finding AT7s as well as Ax7s crapping out.....and not just in one amp or slot either.....
and if it IS a "bad batch" - it does not really inspire confidence in the future for me.

fwiw....not talking about tone, but both Tungs and Eh's kinda look and feel chunkier in construction and dont glow as bright.

 

[misterwhizzy]

Re: JJs

I'm considering a JJ ECC82 for my PI to get rid of some of the buzziness when the gain is cranked and give me better clean headroom. Hopefully I get one from a better batch.

Good call. It made a great improvement in the feel of my amp, especially since it's lower wattage, and a 12AX7 in mine really drove the power amp hard.

 

[Chickenwings]

Re: JJs

what is a ecc82?
81s are AT7s and 83s are ax7s.....

 

[JeffB]

Re: JJs

U7, I believe

 

[Chickenwings]

Re: JJs

aha

 

[Edgecrusher]

Re: JJs

I dont think its so odd that you had both at7's and ax7's crap out. I'm not positive about JJ's but i know here they dont make them side by side they will do a run of one then a run of the other. So its possible if they get a bad batch of metal or coatings or something that it winds up in both tube types.

I think Jeffb did hit on something though. Its not just the tubes you buy but who you buy them from. Here I can get shuguang 12ax7's for down around 80cents each if i buy enough. But they are 100% untested unsorted. Ive found they have an infant mortality rate of around 40%. These are tubes that flat die in less than 6 hours of use. Out of those that do live I then get the pleasure of sorta out the gems from those that sound like butt. When you spend 15 bucks for a groove tubes 12ax7 you do get something and its not just the pretty silk screening on the side. I know even good vendors can get bad tubes but the odds of getting a bad batch from them are a lot lower.

 

[IanBallard]

Re: JJs

Whizzy:
heheh...nah i use tung sols, EH and jjs - both preamp and poweramp slots. I also have an assortment of old tubes that i have replaced with one or all of the above. Ive also used sovteks a fair bit, but only if they are there already. I just like the tone of jjs, so i usually have them in the first preamp slot.
I will admit that i have had other brands of tubes die on me, im juts kinda frustrated cos its not only the fact that 3 have died this week, but also that under normal operation i have found other tubes to work better (less noise, less heat etc). until i bought this most recent set of 10 jj tubes ive never noticed any issues outside of "every now and again".

Ian:
yeah maybe a bad batch....i bought a whole bunch at once, but its odd that im finding AT7s as well as Ax7s crapping out.....and not just in one amp or slot either.....
and if it IS a "bad batch" - it does not really inspire confidence in the future for me.

fwiw....not talking about tone, but both Tungs and Eh's kinda look and feel chunkier in construction and dont glow as bright.

If you got them from the same shipment, it's possible they got dropped, mangled or similar, making them unstable. It's not impossible. The two EH EL34's that were in the back of my amp when I got it, were horrible when installed and the amp tech chalked it up to abuse from them being hauled around in the storage compartment too long.

Personally I think tube makers need to put them in less wimpy boxes with padding of some sort.

 

[IanBallard]

Re: JJs

I dont think its so odd that you had both at7's and ax7's crap out. I'm not positive about JJ's but i know here they dont make them side by side they will do a run of one then a run of the other. So its possible if they get a bad batch of metal or coatings or something that it winds up in both tube types.

I think Jeffb did hit on something though. Its not just the tubes you buy but who you buy them from. Here I can get shuguang 12ax7's for down around 80cents each if i buy enough. But they are 100% untested unsorted. Ive found they have an infant mortality rate of around 40%. These are tubes that flat die in less than 6 hours of use. Out of those that do live I then get the pleasure of sorta out the gems from those that sound like butt. When you spend 15 bucks for a groove tubes 12ax7 you do get something and its not just the pretty silk screening on the side. I know even good vendors can get bad tubes but the odds of getting a bad batch from them are a lot lower.

Good points but Groove Tubes uses re-branded Shuguang from time to time.... however, they are pretty rigorously tested. But most prominent tube vendors test tubes fairly extensively: JJ, Electro-Harmonix, GT and most of the branded Reflektor-made tube brands.

I've worked in plenty of warehouses and know all about shipping and they way truck lines treat their crates. I think tubes, like light bulbs, are subject to constant murder-by-carrier issues.

 

[IanBallard]

Re: JJs

what is a ecc82?
81s are AT7s and 83s are ax7s.....

I've considered an AT7 for the PI like Fender uses, but they have a lower current than a U7 and low gain + high current is supposed to make a more efficient "switch" for the phase inverter, giving you a good linear signal path. My Crate has a "Fender-like" clean channel, so I'm hoping it will give me a good compromise, since the lead channel is "Marshall-like".

FWIW, I'm ordering a pair of JJ 6CA7's.

 

[Edgecrusher]

Re: JJs

That was exactly my point though you can buy shuguang from GT where they have been tested and burned in and have a better chance of getting a good tube even shipped cause GT's do come in nicer boxes or you can buy them from Tobys discount tubes and have them shipped to you in the white box with little to no testing or sorting.

You can buy white box reflectors they are the same ones GT and Ruby and everyone else buys the difference is in the sorting. Yes you are right shipping can have a lot to do with it.

 

[Scott_F]

JJs

They say 95% of tube amp problems are the tubes. I guess that's why they are so easy to replace.

 

[Chickenwings]

Re: JJs

I've considered an AT7 for the PI like Fender uses, but they have a lower current than a U7 and low gain + high current is supposed to make a more efficient "switch" for the phase inverter, giving you a good linear signal path. My Crate has a "Fender-like" clean channel, so I'm hoping it will give me a good compromise, since the lead channel is "Marshall-like".

FWIW, I'm ordering a pair of JJ 6CA7's.

i installed EH6ca7s in my musicman fwiw....epic sounding tubes!

 

[drew_half_empty]

Re: JJs

I like their power tubes, but i only really use their pre's if i got nothin else layin around

never had a problem with em though

 

[Koreth]

Re: JJs

I've never killed a JJ preamp tube. I don't care for their sound, as they sound rather dark to my ears, but I've never had one go out. I have seen a JJ E34L wear out to the point where it got gassy and started arcing at ilde (beautiful looking and loud purple glow with the speakers connected to the amp), but that was after a few years of use. It was due to wear out anyway.

I'd bet a bad batch of tubes escaped the factory, or somewhow got damaged in transit.

 

[guitfiddle]

Re: JJs

I had a JJ EL84 go seriously red-plate after only four hours...stuck the GTs back in and used them for another two years. Haven't really tried any more JJs.

 

[Wattage]

Re: JJs

I haven't had any positive experience with JJ's yet. They never sound right to my ears and they've blown up in 2 amps. I am sure they are not all bad but I have no interest in them at all.