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I have been pratting around with mods to my Marshall JTM60 as mentioned elsewhere. The time has come to reassemble it, but I noticed some intermittent noise when I powered it up. Removing the phase inverter (V4) made no difference, so the problem was clearly in the output stage. At this point I remembered that when my son's TSL100 started doing this it was actually the EL34s that were the problem. I put in a pair of NOS JJ E34Ls and the problem went away.

So my collection of valves consists of:
1 pair Svetlana EL34s; one is good, one microphonic. I replaced them with JJ E34Ls when the one went microphonic causing horrible feedback.
1 pair of Mesa EL34s, both are good (in Matt's TSL100, not sure how much they were gigged)
1 pair of JJ E34Ls, both are slightly noisy (in Matt's TSL100, , not sure how much they were gigged))
1 pair of old JJ E34Ls; they've been in the JTM60 for a few years and one is very noisy while the other seems to start noisy and settle down a bit.
1 pair of NOS JJ E34Ls, same vintage as the noisy ones.

Just for now I've put the quiet Svetlana and the least noisy old E34L into the amp. I'm not too fussed about matching them at the moment.

Are there any other EL34 users out there, and what has your experience been with different brands? I'm tempted to try something other than JJ if JJs always go noisy.

[Edit; added Matt's JJ E34Ls]

I’ve only ever had JJs in my 6100 as they were I think in general the most affordable and I’ve blown one in I think 20+ years of owning it and I’ve not had one go noisy

The amp went back to Marshall when the HT fuse kept blowing in 2009 and they did a general checkup and retube then and it’s been fine since

I’m not the best frame of reference though as that amp is now only used once a month or so since 2015 when I moved away from my band *thick heavy tears of sadness*

Thanks for the feedback. I just remembered I also looked at a pair of JJ E34Ls out of Matt's TSL and they were slightly noisy too.

My DSL50 only ever saw JJ EL34s and then JJ E34Ls, as they were supposed to have more headroom due to higher plate voltage or something.

I didn't have any problems with either, but this was like 10-15 years ago now; perhaps their QC has dropped off since.

Yeah I mean the last time Andy and I retubed our Amplifiers transistors were a new exciting technology

I remember blasting that sweet upper midrange sag into the faces of the cool cats at the ice cream social

I've only used JJ tubes in whatever I've owned at the time. Don't think I've retubed the origin 20H yet. That's current sitting under the bed collecting mojo dust for when I get to be a weekend warrior in my 50's

The SED winged C was probably one of the best out there, but they closed up shop several years ago. When that happened, Diamond amps went as far as to declare the EL34 dead, and switched all of their products to 5881's or 6L6's!

http://www.diamondamplification.com/5881-conversion

I've used EH 6L6's before and had luck with them, but I haven't tried their EL34.

Svetlana was the EL34 standard bearer for a while. The urban legend of the original block logo 5150 Peavey amps sounding better than the script amps was supposedly due to using Svetlana tubes instead of cheaper spec stuff. Those might be worth a try.

JJ tubes all the way. with the exception of the '72 bassman 100 head which still had its original RCA valves, all my tube amps get the JJ treatment. before that, i went with groove tubes as they were in most newer fenders and guitar center tended to carry them in stock.

specific to EL34's, the only time i've a JJ fail was at a venue that blew up my TSL 100 -- blew the fuse, blew a power tube. killed the guitar player's amp of the band after me, too, so i was convinced it was a house power issue and not my amp or tubes. never had a problem with them before or since. i do not notice JJ's being any more or less noisy either.

admittedly, the last set of tubes i bought was a set of JJ's for the AC30 (EL84s) which i didn't have to bias. and now that i think about it, i haven't even so much as looked at the tubes in the prosonic mickie sold me last year. i've plugged it in like three times. since i don't have the stuff to bias it myself, i wouldn't change the tubes on that one right now anyway, but i do plan to use that amp in a future live performance... someday...

pretty much always used JJs without any issue. Never had one go bad.

Just had the other old JJ EL34 in the JTM60 go unacceptably noisy and replaced it with a NOS JJ EL34L. The Svetlana continues to be quiet.

JJ's have supposedly been mostly okay with supply chain, too, but i'm not sure about the individual resellers.