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JJ = Just Junk?

BuzzK

BuzzK

AK Member
Subscriber
I bought a couple of "matched" quads of JJ EL84s from Viva and Tube Depot to populate a pair of SCA-35 amps. When buying quads now, I think it's a good idea to get 5 matched tubes instead of 4, in case one dies.

I built my own tube matcher, and the quad wasn't what I would call a good match. The proof was after installing them in the amps with Dave G.'s EFB, I couldn't get both channels at 0.27 mA.

In less than an hour, one of the new JJ's blew the line fuse of the amp. I noticed that it was now dark when the amp was powered up on a variac (where I could keep an eye on the current). It appeared like there was a spot of fresh getter material on the side of the tube.

I now have two bad JJs, trying to get two quads out of the mix.

My experience may be an outlier, and not a representative or fair sample. I am disappointed . . . I was hoping that JJs would be a good alternative to Russian tubes no longer being made.

Do other folks have good or bad experiences with this brand?
 
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Sorry your having issues.
I haven't had any issues with the JJ EL 84s or the 12AX7's that I bought a few years ago. The EL84s were in my ST70 for a couple of years so they have a decent amount of hrs on them.
 
I have some JJ KT77s I run in Kegger's ST70 and they gave me no issues. They currently aren't installed as I rolled in some Russian EL34s with broken keys months (years?) ago and they are fine for my background listening.
 
BuzzK said:
I bought a couple of "matched" quads of JJ EL84s from Viva and Tube Depot to populate a pair of SCA-35 amps. When buying quads now, I think it's a good idea to get 5 matched tubes instead of 4, in case one dies.

I built my own tube matcher, and the quad wasn't what I would call a good match. The proof was after installing them in the amps with Dave G.'s EFB, I couldn't get both channels at 0.27 mA.

In less than an hour, one of the new JJ's blew the line fuse of the amp. I noticed that it was now dark when the amp was powered up on a variac (where I could keep an eye on the current). It appeared like there was a spot of fresh getter material on the side of the tube.

I now have two bad JJs, trying to get two quads out of the mix.

My experience may be an outlier, and not a representative or fair sample. I am disappointed . . . I was hoping that JJs would be a good alternative to Russian tubes no longer being made.

Do other folks have good or bad experiences with this brand?
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What does the vendor say ? I assume they warrant their products.
 
peterh said:
What does the vendor say ? I assume they warrant their products.
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That's a very good question. Unfortunately, I ended up testing about 20 tubes in the 6BQ5 / 6P14-EV family last night about midnight, and I missed up the JJ tubes while trying to find a decent quad . . . so I don't know who sold me what. My bad.

Viva offers a 45 day warranty on tubes. Tube Depot's warranty is 90 days, FYI. I'm probably past the first and maybe the second. . .
 
I haven't had a single issue with JJ signal tubes. I acually like them when it comes to new manufacture. But I have had a JJ KT-77 with low hours fail along with a couple JJ 5AR4's. I had bought a Quad of JJ KT-88's to try in my VTA
ST-70, but didn't like how they sounded in that amp. When I bought and built a pair if VTA M-125 mono blocks I bought a second quad of JJ KT-88's since I already had a quad. In these amps they sound fine and so far no issues.
It seems like quality control with some of there power tubes and rectifiers aren't very good, or the construction is just poor to begin with.
 
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No issues with JJ. I have sets on hand that I've used for hours in my HIFI amps to proof them, now spares or for future projects as needed. They include KT77, KT88, 12AX7, 12AU7 and 12AY7. Only problem was with one of the 12AY7, but I think it was my fault, tried to bend a pin and the glass broke loosing vacuum. It was OK when I had it in the circuit.

My Ampeg V4B reissue came new with a full compliment of JJ tubes. 3 12AX7s, 1 12AU7 and 4 6L6GC. I also have spares JJ 6L6GCs for my smaller bass amp. I prefer the Tung Sol 6L6GC STR or 7581A for that one, but not due to JJ reliability.

I've not tried a JJ 5AR4 for any amount of time. I have one but only used it for a short time in a Ampeg B15 clone. I ended up going Genalex and Tung Sol for rectifier tubes in everything I have that uses them.
 
BuzzK said:
That's a very good question. Unfortunately, I ended up testing about 20 tubes in the 6BQ5 / 6P14-EV family last night about midnight, and I missed up the JJ tubes while trying to find a decent quad . . . so I don't know who sold me what. My bad.

Viva offers a 45 day warranty on tubes. Tube Depot's warranty is 90 days, FYI. I'm probably past the first and maybe the second. . .
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So far, I'm really liking the 6P14P-K's I bought. I'm using them in a Maggie PP 9303 and the DG1 SE amp I built. I've thought about trying a quad of the 6P14P-EV's in my Dynakit ST-35.
 
tubelectron said:
Yes, that's questionable...

For a time (circa 10-15 years ago) JJ power tubes prone to failure or even unusable right out of box brand new was not so uncommon : I had many problems with 6L6GC, EL34, 7591 and EL84 showing : interelectrode shorts or leaks, F/K leaks, filament shorted, excessive plate current giving red plating or red screening, etc... So far that I discarded the brand when installing replacement sets in guitar amps.

IMHO, this was a matter of quality control in production (maybe under the Milosevic era - he was the undue owner of JJ before confiscation), but things have presumably changed since, because that kind of failure is now rare...

T
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Milosevic has never been involved in JJ. Milosevic is a serb from serbia, JJ has tjeckoslovakian roots from TESLA factory
in prague, but moved to the slovakian republic after tjeckoslovakian break up.
 
Vacuum tube QC will never again be what it was in the 1940s-1970s when they had the best engineers designing them and great factories producing them.
I have had so many Russian tubes fail (on their own - no fault of the equipment) over the years, which is part of what got me really interested in the NOS tube thing.
 
byoungman1 said:
Vacuum tube QC will never again be what it was in the 1940s-1970s when they had the best engineers designing them and great factories producing them.
I have had so many Russian tubes fail (on their own - no fault of the equipment) over the years, which is part of what got me really interested in the NOS tube thing.
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I must be doing something wrong, I've had more problems with old tubes than new production tubes. :dunno:
 
I really like the JJ small signal tubes, and use them in most of my own equipment, both home audio and musical instrument.

The JJ EL84 is a tube many people I know personally swear by for their Vox AC30's (and clones). This is a really unfriendly environment for four EL84's, sitting right behind a pair of 12's. They usually die of old age or get such a case of the rattles that they need replacement. Mind you, these amps are cathode bias, which I have found gives power tubes an easier time.

I tend to stay away from their octal offerings, based only on "reputation", for whatever that's worth. Although, the E34L has proven to be darned near indestructable, even in my Hiwatt Tube State 200 power amps, which run six E34L's at over 650V on the plates.
 
Haven't bought any JJ Quads for more then a few years. So all I can go by is past experiences with them. They have performed as well as the Tung-Sol Mullard TAD that have purchased the resent past. In fact was running a Quad JJ EL84's in a pair of Mono Eico's until doing a volume buy on 6P14P's with a friend right before the supply went crazy.

That stated haven't bought any new for the past two years. So have no way of knowing what the current production quality is.
 
I have used JJ's for years and haven't had a problem until recently. I've had 3 6CA7's redplate, one right out of the box, 2 after a year of barely being used, unfortunately out of warranty. The customer is not happy. I will never use their tubes again, going back to Electroharmonix.
 
arts said:
I really like the JJ small signal tubes, and use them in most of my own equipment, both home audio and musical instrument.

The JJ EL84 is a tube many people I know personally swear by for their Vox AC30's (and clones). This is a really unfriendly environment for four EL84's, sitting right behind a pair of 12's. They usually die of old age or get such a case of the rattles that they need replacement. Mind you, these amps are cathode bias, which I have found gives power tubes an easier time.

I tend to stay away from their octal offerings, based only on "reputation", for whatever that's worth. Although, the E34L has proven to be darned near indestructable, even in my Hiwatt Tube State 200 power amps, which run six E34L's at over 650V on the plates.
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I have read various posts on other forums where the JJ EL-84's hold up well in guitar amps and the Dynaco ST-35. Guitar amps can beat the snot out of tubes.
Like you, im perfectly happy with JJ 9 pin signal tubes. For octal, I like Tung-Sol.
 
dr*audio said:
I have used JJ's for years and haven't had a problem until recently. I've had 3 6CA7's redplate, one right out of the box, 2 after a year of barely being used, unfortunately out of warranty. The customer is not happy. I will never use their tubes again, going back to Electroharmonix.
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Was going to ask about them now that EH isn't an option.
I've had two EH do the opposite of red plate, effectively going open circuit. Still prefer them.
 
Only JJ tubes I have are EL34. of my selection, the JJ are electrically and sonically most similar to my old Mullard EL34 tubes. They work fine, but admittedly I don't have tons of hours on them. They were used tubes that I got stupid cheap. Think I paid 40 for the quad.
 
peterh said:
Milosevic has never been involved in JJ. Milosevic is a serb from serbia, JJ has tjeckoslovakian roots from TESLA factory
in prague, but moved to the slovakian republic after tjeckoslovakian break up.
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Prolly got mixed up with Ei. These were once made in the Serbian region of Yugoslavia.

JJ has had a history of hinky batches of some output and many rectifier tubes, since the 1990s. You need to buy from a dealer that tests each tube for strength, quiet use, and any leaky issues.
 
I bought some JJ ECC83 two or three years ago, and they hummed in my preamp. No other tubes have ever done that. Then I tried to put them into a customer's power amp, and the tubes are so non-linear that it wouldn't put out full power with JJ tubes, but will with any other 12AX7 the amplifier works fine. Basically just feel like I threw my money away. Bought from Antique Electronic Supply, who wouldn't take them back because they test good. So not some eBay purchase.

I've seen their EL34s go short circuit in probably a half dozen amps over the years, one instance which ended up burning a hole in a Dynaco ST70/II board, and another burning the board in a very nice French amplifier. I've also seen the KT88s short circuit, destroying the board in a nice Chinese made amp. While one could say that a tube amp which is properly designed should be better protected against shorted tubes (and I agree!), it's statistically significant to me that most of the defective tubes I've seen which have shorted have been JJs, although Russian and Chinese tubes are a lot more common in general.

Never used the EL84. Love their 2A3. I've always been confused by all the good reviews JJs get - I wonder if they keep the good ones in Europe, and ship the rejects to North America?
 
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