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Durable EL84 tubes?

gtone

Asked by gtone,

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gtone Veteran HFCer

gtone

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My EU supply channel of EI and RFT EL84/6BQ5 tubes has run dry and I'm in need of some durable, low-noise/low microphony tubes for my Phaez. It runs at over 400V on the plates and is an open-back combo that gets played out now/again.

Recommendations? Happy to get input from you EU guys too, as there maybe something else I'm missing from that side of the pond.

(Anyone have a line on some of those rare Seimens/Halske E84L's, perhaps? ;))

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crunchee Veteran HFCer

crunchee

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How often are you going through EL84s? And, are you changing them out for any particular reason? Do they start losing punch, or are they getting fried?

Just speaking for myself, when I'm shopping for a tube amp, I consider how hard they are on tubes even BEFORE I make a decision...which is why I like Fender tweed amps, they don't try to squeeze ALL the power out of the tubes all at once.

gtone Veteran HFCer

gtone

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How often are you going through EL84s? And, are you changing them out for any particular reason? Do they start losing punch, or are they getting fried?

Power tubes generally last from 6 months to 2 yrs in that amp. Randy Fay says that's about normal for the DaisyCutter model given it's bias and plate voltage. I've fried tubes a couple of times, once spectacularly taking out a screen grid resistor in a cloud of smoke. Most of the time, they just wear out - lose volume, punch and the highs become attenuated. More sets have gone microphonic than not with better ones taking a few months to get there, some of the lesser of have developed/exhibited microphony the first or second time the amp gets pushed to stage volume. (Note: I use the the silicone retainer rings/bands).

Polam/Telams were dead quiet but wore out in 6 months. Set of JAN Philips sounded very nice, lasted about 1 yr. Had a set of JJ's that lasted about 2 yrs, but they were getting noisy by the end of that. The EI's/RFT's generally lasted anywhere from 6 mths - 2 yrs, great luck with the first couple of batches, a little less so with the second couple of sets, sounded good and the price was right ($25/ea), so kept buying them. Had a Chinese set in there that sounded ratty, went microphonic within a couple of uses so in the trash they went. The Sovtek's that Randy shipped the amp are my backups - fairly reliable as much as I've used them, but they sound a bit harsh too (better than the Chinese ones though).

it's me HHB Veteran HFCer

it's me HHB

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I've had the same Electro Harmonix brand in my Tophat Club Royale for several years, like 5 or 6, and that amp gets used a LOT. How long can they last?

gtone Veteran HFCer

gtone

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Wow. JAN Phillips wore out in a year? Military Production?

Yep - JAN stands for "Joint Army/Navy" which means they were built specifically to the US military's high standards.

crunchee Veteran HFCer

crunchee

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Wow. JAN Phillips wore out in a year? Military Production?

Yep - JAN stands for "Joint Army/Navy" which means they were built specifically to the US military's high standards.

Not just military standards, but military use, too...they're meant to be used in relatively harsh conditions. But a + 1 on the 1 year lifespan, that's not very long for semi-regular use.

tomteriffic Veteran HFCer

tomteriffic

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Sheebus! Where is your bias set? If you're going through JAN tubes at that rate, it has to be way high. The tubes in Fender amps last as long as they do because they were biased way cold at the factory. That's the other side of the "lasts forever/tone of the gods" equation.

JohnnyB Veteran HFCer

JohnnyB

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I have a Trace Elliott Velocette15w 1x10. Has great tone. I haven't played it for quite awhile, but when I did (around 1999) it was running through Tesla JJs with casual use within months. I figure it has a very high bias. Then I replaced the EL84s with NOS (50s? no later than 60s) GE 6BQ5s. They haven't gone out since, and my daughter was playing it daily with her HS jazz band for 3-4 years.

gtone Veteran HFCer

gtone

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IIRC, believe the JAN Philips were the ones that fried out on me, as I don't recall them ever getting microphonic. Was pretty much using that amp daily back then (not as much now as I spread the joy over more amps these days).

The DaisyCutter platform is relatively high gain - roughly somewhere around a hot-rodded Marshall (tone is its' own thing, however). Don't know the bias setting per se, but Randy did the replacement of the screen grid resistor following the melt-down, checked the amp over and deemed it otherwise healthy. We'd spoken about the short lifespan of the power tubes in the amp, but he put it down to the smaller bottles in a hostile environment; in other words "nature of the beast".

And yeah - I'm well aware of lengthy tube lifespan with the old Fenders. I've owned Tweeds, BF's and SF's and every one had one or more of their original tubes in it from what I can gather. The Phaez is a kinda the polar opposite of any Fender I've owned, however. For that matter, I believe the Fender Blues Junior can be a little hard on EL84's, albeit that may be in relative terms compared to their more common 6V6 and 6L6 powered models.

Jakeboy Veteran HFCer

Jakeboy

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I have a pair of Japanese Matsushita EL84s that test new out of an old Baldwin organ that I would sell pretty cheap or trade. Let me know if interested.

RobB Veteran HFCer

RobB

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I didnt think el84 needed biasing

They don't if the amp is cathode biased (AKA self-biased):

http://www.mackamps.com/articles/what-is-guitar-amp-bias.html

No affiliation with the writer of the article or the company.

My amp tech re-biased my Subway Blues combo. Sez that the bias on that model is usually really hot and burns tubes fast. Odd, because I had always heard Boogie biases their amps pretty cold. Whatever he did, it sounds great with the new tubes/adjustment.

Jakeboy Veteran HFCer

Jakeboy

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So many el84 amps run hot.....AC30s are notorious for it. My Lil Dawg Pug was cathode biased and I found that Chinese Mesa tubes ran VERY well in the power section, but not as good as Used ANOS Mullards. I would look for quality old US, European, or Japanese tubes that test 100%. I used current JJs and they sounded fine too. I did get several years out of the Mesas though, before I slammed in the Mullards.

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