Modern EL34 reliability?

[tubeswell]

Sovtek EL34G's were not very good back in the day and they are likely just as bad now.

Greg

I would agree that Sovtek EL34G are not consistently high quality, but they are still fairly cheap and if you buy enough of them you can make up a set where the bias is stable. (However, one really ought to buy twice as many as you think you'll need to get a matching set that is going to hold up).

[soundmasterg]

Is the vacuum spec of EL34 really different to beam tetrodes etc?
I thought that claim was another example of Aspen Pitman's nonsense technobabble.
Surely if the vacuum wasn't good the getter would get all used up quickly and the tube fail?

The El34 was a cheaper tube from the beginning because it was a lower vacuum tube than something like a 6L6, so it needed less time before it was ready to sell. Since it is a true pentode, it will always have more screen dissipation than a beam tetrode too. The modern El34's and all modern tubes in general don't have the same vacuum specs as the older tubes. The manufacturers just don't spend the time necessary to get them to where they should be, so due to that and other reasons, they fail quicker than the older tubes did. The Vacuum Tube Valley publications had some good info on that. I think Eric Barber wrote those articles.

Greg

[soundmasterg]

I would agree that Sovtek EL34G are not consistently high quality, but they are still fairly cheap and if you buy enough of them you can make up a set where the bias is stable. (However, one really ought to buy twice as many as you think you'll need to get a matching set that is going to hold up).

I'd just as soon use about any other EL34 type myself. I think especially in higher voltage circuits the EL34G just can't hold up. I'm talking 500V+ circuits.

Greg

[TimmyP1955]

Other than JCM2000s, what Marshalls have runaway issues? I've not seen it, but for the most part I encounter only JCM900s and JCM800s.

[Chuck H]

I haven't either. But I don't do that many repairs like some pro's here. I usually see Marshalls fail because they aren't plugged into a load or the load is compromised by a bad cable or dirty connection. But of course they fail for other reasons. I haven't seen runaway, but I've read about it being peculiar to one model (one of the 800's I think). I remember it was, perhaps, a layout/oscillation issue. I'd love to get one on the bench. I sort of like snarky problems and their associated frustration (as long as I eventually come out on top )

[Justin Thomas]

I'd love to get one on the bench. I sort of like snarky problems and their associated frustration (as long as I eventually come out on top )

And this is why our bench is ALWAYS located near a window, preferably a second-story window, with a dumpster below it. You always come out on top.

Justin

[The Dude]

Other than JCM2000s, what Marshalls have runaway issues? I've not seen it, but for the most part I encounter only JCM900s and JCM800s.

The JCM2000's with certain serials are the only ones I know of with an inherent bias drift problem due to conductive boards. Of course any amp could have similar problems for other reasons.

[tubeswell]

Other than JCM2000s, what Marshalls have runaway issues? I've not seen it, but for the most part I encounter only JCM900s and JCM800s.

1959 RI handwired. The PT is wound to deliver ~520 plate volts and about 507 on the screens, but the bias tap and 'stock' bias supply circuit barely manages to deliver -40VDC, and needs modifying. The one's I have seen are biased absurdly hot.

[blindboybenton]

I know this is a long and old post but i thought i would say something

Over the years i have tried them all. I stopped using JJ EL34 a few years ago, , due to the fact i have a high failure rate. moved on to
Tung Sol or TAD without having any issues, and if customer on a budget Ive used EH with 0% failure I moved the workshop to a local guitar shop about 18 months ago, and as they are Marshall Dealers, I decided to start using Marshall branded TAD tubes, I can safely say ive had zero failures with any tubes . I tend to Buy EL84 and EL34 from Marshall and they are cheaper too .. I use a UK supplier for every thing else

BBB

[J M Fahey]

Also had lots of problems with JJ, with the added nag that tubes are expensive here (double than in USA), there´s a very limited variety to choose from (the Market is tiny, so an Importer brings a fridge sized box of, say, JJ in and that´s what´s on the menu, period, until they are all sold and he brings another one, usually a different brand,and so on) and to boot "everybody knows that JJ are very good, "European" ,not like those cheesy Russian or Chinese tubes" so general perception is that "if they fail it´s because Juan did something WRONG"
So I did get dogs and I had to eat them too, losing money in the process.
Whay do I do now?: I do NOT sell tubes, period (otherwise I´m "married" to them for life), but if , say, 4 EL34 are needed, I ask customer to bring *six* of them.
I measure them in my own jig , 4 "best" go into the amp, typically the 5th is marked as possible future replacement, (even if weaker "today" , by then original ones will have worn some, so *then* it will more or less match them) ... and the 6th may typically range from "old worn spare tire" , to be used only in an emergency (say Friday/Saturday Night in the middle of a show) to dustbin fodder (too gassy, internal shorts, sparking, self redplating, whatever).
If/when tube fails customers are courteously invited to bug tube supplier for replacement/refund/whatever ... not me.

If I need some for a project of my own, I buy "rebranded" ones such as "Fender" or "Marshall" tubes, I know they don´t get the bottom of the barrel/rejects ones which reach these shores.

Absolute worst case and if nothing else is available, I buy Sovtek or EH 6L6/5881 , Russians can be trusted making those, even Chinese are not that bad, and if necessary rebias amps for them ... EL34 land is a minefield.

[Chuck H]

... EL34 land is a minefield.

Amen.

But I've never heard 6l6's bloom and swirl like el34's.?. Maybe it's a beam tube vs. pentode thing? I sure wish I had a handle on it though. The guy that learns to make the reliable tubes sound like the coveted tones will own the boutique market. And that bloom and swirl (without sounding like crossover fizz) is the most important element. No one has ever done it with any small bottles. I've been trying to get el84's to do it for years with no luck.

So for now we're stuck with the el34's. Only the Shuguang tube actually sounds and behaves right and is typically up to the voltages in older amps. Unfortunately they tend to be microphonic right out of the box IME. Since most Marshall amps are heads it works out for most users. In fact I've recognized that the Shuguang el34b tube selected and rebranded by Ruby is probably the most endorsed tube on the Marshall forums. How long before that changes as well though? Useful el34 models have been dwindling since the early 90's. Maybe (though I hope not) the el34 guitar amp thing will be the first of many coveted tones that will end in a file labeled "history". Gone forever

[m1989jmp]

I know this is a long and old post but i thought i would say something

Over the years i have tried them all. I stopped using JJ EL34 a few years ago, , due to the fact i have a high failure rate. moved on to
Tung Sol or TAD without having any issues, and if customer on a budget Ive used EH with 0% failure I moved the workshop to a local guitar shop about 18 months ago, and as they are Marshall Dealers, I decided to start using Marshall branded TAD tubes, I can safely say ive had zero failures with any tubes . I tend to Buy EL84 and EL34 from Marshall and they are cheaper too .. I use a UK supplier for every thing else

BBB

That's strange because I've never had JJ EL34/E34L/EL34II fail on me. On the other hand, the only Tungsol EL34 pair I tried failed after a few months (one tube developed runaway bias current).

Also, it is my understanding that Marshall uses JJ EL34 as their stock tubes.

[Enzo]

Statistics don't apply to individuals.

[blindboybenton]

That's strange because I've never had JJ EL34/E34L/EL34II fail on me. On the other hand, the only Tungsol EL34 pair I tried failed after a few months (one tube developed runaway bias current).

Also, it is my understanding that Marshall uses JJ EL34 as their stock tubes.

In the uk marshall stopped using JJ tubes EL34 about a couple of years ago. They now supplied TAD or Tung sol..
I think the rep told me that they have had the same issues with EL34 failing early. They still use JJ in the EL84, But whenever i order EL84 from them i get TAD
BBB

[m1989jmp]

In the uk marshall stopped using JJ tubes EL34 about a couple of years ago. They now supplied TAD or Tung sol..
I think the rep told me that they have had the same issues with EL34 failing early. They still use JJ in the EL84, But whenever i order EL84 from them i get TAD
BBB

I've seen 50H Origins supplied with JJ EL34s, but with somewhat different design (JJ on the base, Marshall logo, etc.). I guess they still use them in their budget amps.