Problems with JJ 12AX7 Types

TheAmpNerd

Member
Messages
1,056
Gang,

Anyone else having problems with these tubes?
ECC83S
ECC803S

More than 50 percent of my installations
of these tubes lasted a few gigs then
when south?

These were all in various amps too.
 

jmadill

Platinum Supporting Member
Messages
595
I don't know if this applies to their preamp tubes or not, but I was just reading on the Webber BiasRite site that the JJ power tubes have smaller diameter pins that sometimes don't make good contact.

-jm
 

VacuumVoodoo

Member
Messages
1,547
Do you know if they were getting too high heater voltage? New amps or vintage? Mains going high on amps made for old 110-115V ?
 

rockon1

Platinum Supporting Member
Messages
12,981
Ive had problems with the long plate ECC803s. 3 out of 6 went bad in a short time. Of all the ECC83s I have only one went microphonic on me. This was mostly in my JSX.
 

Swarty

Member
Messages
1,130
I don't buy them as I've serviced several amps over the last year or so with problems that turned out to be bad JJ 12AX7s.
 

Scumback Speakers

Platinum Supporting Member
Messages
10,849
I buy mine from Bob @ Eurotubes. Every time I get them for other sources I have a high failure rate. When I get them from Bob, he weeds out the bad ones in advance.

If I don't get them from Bob (and I have) I get a 25-50% reject rate, with Bob, I've had ONE bad tube, which he promptly replaced for free including the shipping charges and didn't ask me to send the bad one back.

Yeah, it costs $2 more per tube, but you'll spend more than that on each tube plus the hassle, so I'd rather buy them from Bob. Here's his site for those interested.

http://www.eurotubes.com/index.htm
 

TheAmpNerd

Member
Messages
1,056
VacuumVoodoo said:
Do you know if they were getting too high heater voltage? New amps or vintage? Mains going high on amps made for old 110-115V ?
Both vintage and new amps.
A few were older Fenders '64 '67, '70, '73
The others were two modern Fenders,
hot rod deluxe, deville,
a vintage marshall, the others
were a couple were hand made amps.

Different tubes fixed the problem.
I still hate having to suck it for tubes.

Goes with the Territory.

Thanks for the info too.

I guess it is either bob or lord valve.

 

Carol-AnnAmps

Member
Messages
4,855
I've used 200 JJ's in the last three months and not had any failures.
However I buy them pre-selected and tested from a reknown wholesale distributor. If you were to get a batch straight from the factory the failure rate would be somewhere between 30-60% depending on the batch.
 

thintele

Member
Messages
775
I have very good luck with the JJs ECC83s ...I buy mine from Revolution Guitar and haven't had one go bad yet. I have not tried the ECC803s but Glassman did a shoot out with clips of several different 12AX7s and IMOP the ECC803s was one of the better sounding tubes, even compared to some of the NOS tubes, but I cannot speak for its reliability
 

rooster

Member
Messages
2,119
I've had nothing but good luck with them. I get them by the dozen from Antique Electronics, who doesn't do much in the way of QC (I believe), unless they pay JJ extra to sort them ahead of time. I've not gotten any bad ones yet. I did have a couple bad AU7's a coupla years ago, but not since.

I go through quite a few building amps, but the JJ's have always been VERY reliable for me.

rooster.
 
Messages
347
Actually, in my D/13 RSA 23, I purchsed a new set of JJ KT88 power tubes from Bob at Eurotubes (these babies are expensive anyways) and I noticed that the tubes were SUPER loose when I placed them in. Is that really bad? Maybe not getting enough contact to the pins or could the pins be too small?
 

electroid

Member
Messages
202
I've sold hundreds of JJECC83 and had very few problems with them. Far less than any other brand.

As for power tubes, yes the pins are too small. You need fresh sockets or you need to tighten the sockets to make them stay connected. This does not apply to their 9 pin tubes. However, JJ is starting to release some power tubes with bigger pins now. I just received a new batch of JJ 6L6 and the pins are bigger and fit the sockets much better.
 

Hacksaw

Time Warped
Platinum Supporting Member
Messages
10,217
I also retention the power tube sockets as described in EuroBOB's included info sheet (he sends with every set). if the tubes are loose in the sockets you may experience HV arcing! retention sockets asap!

I have used JJ preamp tubes from Bob and I havent had a failed tube yet over the past years. Lke others here, I have installed them in many many different types of amps. I recommend them.

Electroid, glad to hear they started using bigger pins! that would be a very good move.
 

lastwinj

Member
Messages
289
+1 on JJ. get them from a reputable dealer. i have a couple out of 30 go bad, but i use them in super high gain amps. the bad tubes worked fine fsrther down the line.
 




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