Tubes...aarrrggghhhh....

[tubedogsmith]

Is it just me. I've had more tube failures in the past 6 months than the previous 6 years. Preamp and power tubes. I quit buying bulk a long time ago because I got sick of sending bad ones back all the time and resigned my self to paying extra to get them tested and matched but I'm starting to wonder. I know a lot of folks give sovtek a bad rap but I've not had any failures with them for years until just recently. I had one tube in two different quads of EL34's replate within an hour of being installed the past two weeks. Similar experience last month with a quad of 6L6 TAD's. JJ preamp tubes are getting wanky as well. I've had at least one of ten not even work when first installed lately. I put a set of Winged C EL34's in an amp after the EH's went and while they seem healthy they don't really sound all that great. I replaced them with an older set of Wnged C's and the difference is night and day. I've still got a bunch of late '80's chinese preamp tubes but I've been trying to save them for specific spots but I've needed to use them everywhere lately. Anyway, just venting.

[Structo]

I haven't bought any tubes in a while but what you are saying seems to be going around.
QC has slipped.
Possibly the economy where the factories are not tossing questionable tubes any longer because of the bottom line and sellers are not screening them as well.

Sucks.

When everything ran on tubes, there was much better competition.

[selloutrr]

Sorry that really sucks!

Personally knock on wood I've been lucky enough to not experience this.

It puts up a flag, making me wonder which amp is giving you so much trouble and if the it's not biased properly for the tubes. The Winged C is a very hardy tube which would explain it working better but not sound great if the voltage is not correct.

If you continue to have issues outside of that/those amps. You should check out ruby tubes, most of them are russian and china tubes relabeled but they do warranty all tubes for 6 months from the date of purchase.

[tubedogsmith]

It's all been in different amps. An EL34 amp with 428v on the plates, less on the screens in perfect running order doesn't blow tubes biased at 32 mA unless the tube is bad.
There's something different about the recently made Winged C tubes, I've tried two recent quads and both sounded the same but different from older sets.
I've used the Ruby tubes on and off for a while as well. I don't think I've had any fail but I hate looking at all that crooked glass

[Structo]

Something I have noticed with the Winged C 6L6 tubes is a certain amount of harshness when they are brand new.
This seems to disappate after a few hours run time.
Since tubes lose power from the highs down as they age I guess it's just part of breaking them in.
I do have an older pair that I seem to remember sounded great out of the box but that has been a few years ago now. They are still good tubes to this day.

[Max]

I use NOS GE, Sylvania, Amperex, Philips, Mullard, EI and RCA tubes since around 20 years now and had no failures at all up to now. Only exception concerning NOS was that I used some then new Sovtek "5881" tubes in some skyline amps as these had been placed there by Alexander (EI for V1 and 2 and GE for PI) and I felt no need to change them as the amps did what they should in my perception and seemed to be set up for these Sovteks. No reliability problems, too. No experience with new tubes. Maybe the new ones are great too of course. But why should I change a winning team?

Cheers,

Max

[Tonegeek]

It's all been in different amps. An EL34 amp with 428v on the plates, less on the screens in perfect running order doesn't blow tubes biased at 32 mA unless the tube is bad.
There's something different about the recently made Winged C tubes, I've tried two recent quads and both sounded the same but different from older sets.
I've used the Ruby tubes on and off for a while as well. I don't think I've had any fail but I hate looking at all that crooked glass

I tried some Winged C 6L6 in an amp designed for EL-34s and one thing I noticed is they sounded much better biased hot. In my case I have 456V on the plates and biased @ 44ma/tube. Anything less on the bias and they no sound good. I still like the EL-34s better in this amp (biased cold). About failures, more QC is needed at the point of manufacture. I went through a rash of bad JJ El-34s. Now I pay extra and get them burned in. Even at that, they only last a year or so.

[talbany]

Bad tube batches seems to come at me in waves.. I'll get a bad batch here and there mostly within the same order (Especially 34's)..This is where a good tube tester earns it's money..Test them or try to burn them in right away if you find a bad batch call for an RA.. If you don't have a good tester get out the shop amp and burn them in while your soldering..i don't care if it's a pair out of 50 I send em back.. I paid for them they should work..

Tony

[67plexi]

I have had good luck with the reflektor russian 6l6gc made in the 1960's
5,000 hour tube you can still buy cases of 50 each.The el-34 the RFT dimple top are good $200.00 per quad NOS. I think the new made tubes are the oats that have been through the horse.

[butwhatif]

I have been retubing lately w/tungsol 5881 and E-H EL34, and have had no issues---

[David Root]

I'm not a business, I only use NOS and UOS, and the only failures I have had has been UOS RCA blackplate 6L6s that were simply worn out and went to Valvehalla in various ways. They only cost me $10 each so I got my value out of them.

If I were a business I would be tearing my hair, which in my case is pretty marginal to begin with, at these horror stories.

From what I can see the new stuff seldom meets the original NOS specs, even before we get to the issue of reliability, which explains stuff that works OK but doesn't sound right.

The original manufacturing processes would not be allowed today in Western Europe or North America without pretty major clean up costs. On top of that I'm not even sure that some of the old manufacturing "secrets" haven't been lost with the Ancients themselves.

There was that one outfit in the UK that designed and brought to market a new 12AX7 that claimed to meet original specs. $80 each. You can buy nice NOS 12AX7s for that, so I can't see them having a great future until NOS gets substantially higher than $80.

[mojotom]

I've had some bad luck with JJ El34 some years ago so avoid JJ power tubes.
Bought a quad of Wingled C 6L6 (not imported in Europe) for my 124, really like them compare to Tung Sol 5881 with a clearer bass but one made a short after a couple hours. They were bought burned in and with the thermic treatment,no refund either, I had to buy one more tube and it's shipping, wasen't really pleased.

Construction have changed a few yeas ago (I've got an old set with black base) but the main issue is ROHS. All manufacturers had to use differents alloys for plate, grid, etc and it's a very time consuming R&D process both about sound and reliability.

So far, Sovtek seems to have handle the changes properly, JJ is far behind and Svetlana seems to follow old datas and didn't seems to be able to invest as much as Sovtek to adapt.

Fortunately, they will improve the formula for a more robust tube. NOS tubes in good shape are still available and beside some very obvious super expensive brands it's a bargain when you think about sound quality and reliability.