How Many Times Have You Had Your Amp Damaged By New Tubes.

Discussion in 'The Workbench' started by Neil Skene, Apr 21, 2017.

  1. Neil Skene

    Neil Skene Active Member

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    Just finished repairing my DSL100 (Cathode resistor) after a bad set of tubes gave it a flogging.
    I bought six matched sets (24 Bullets) paid extra for testing on four of the sets and one tested set blew up as soon as I took it off standby.
    I know quality control and the materials are pretty poor these days so how many amps are actually being damaged by these tubes. Maybe it was a coincidence and the amp was about to go anyway but I'm not putting the so called bad set back in to test the theory.
    I want to build a a bit of a stock pile so will be buying more soon and another game of Russian roulette will begin. I don't like using my amp to test tubes that are supposedly already tested but what else could I have done.

    A photo of my poor old DSL after repairing. Lucky I had what I needed to repair it or I would have had a headache dragging it around the countryside for repairs.

    Some pretty tube photos.
     
  2. SG~GUY

    SG~GUY Well-Known Member

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    -sorry to hear that Niel, I'd be in touch with your tube vendor, and if at all possible test the suspect's previous to that-(so you know the answer before you ask the question)-

    -I've never had an amp damaged by a tube, period. But I've had tubes red plate-(not as good as your pretty picture thou)-

    -and I have run a high bias on every amp I've had,...

    -I've noticed that this is happening more frequently, here's my theory, more amps are being made in ASIAN countries, countries that for the most part use substandard materials, especially all metal's, a huge % of the world's scrap metal is bought by these countries, the quality of anything metal,even copper is very poor, which leads to these kind of failures, be it the internal components of the tubes or the amp,
     
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  3. Neil Skene

    Neil Skene Active Member

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    I was pretty mad when it happened but have cooled off now.
    The vendor is going to give me a refund but I still want to buy more, so will have to take the risk again and run them all in my amp.
    I know it's not going to happen but I wish someone would make a good quality tube.
    I fear Valve amps are going to end up like film cameras and become obsolete because the Valves, like film,
    will no longer be produced. I dumped a Drum Scanner that cost over $250000 when they were new last year because film photography is dead and there was no work for it.
    Been looking at the Kemper. Shame they look like my Nana's old toaster, maybe in the next few years :hmm:
     
  4. Georgiatec

    Georgiatec Well-Known Member VIP Member

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    I take it you biased the amp after putting new tubes in.....you didn't just drop 'em in then switch on and play did you.?
    I know tested and passed tubes CAN fail. I recently supplied a pair of vintage RFT EL34's to a forum member that I had tested and matched with flying colours, but they had only been in his amp for 15 minutes when one let go. Trouble is you get no warning, you can play a two hour set and sound great, then next time you power up....POP!!!
    It's very unusual for new matched tubes to die though.
     
  5. ampmadscientist

    ampmadscientist Well-Known Member

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    In your bathtub.
    "...and one tested set blew up as soon as I took it off standby..."

    You are simply blaming the tubes:
    for a problem in the amp.

    It seems you have a bad DSL output circuit board..and you are in denial. (or you have a speaker / load related issue)

    You have no test equipment, and you don't know how to troubleshoot and correct the real cause of the problem.

    You are working according to assumptions. This is typical....
    I believe this: (blah blah blah) and it MUST be true, because I imagined it was!

    What you really need here: is a real technician, with real test equipment.
    And you need to realize that assumptions are not reality.
    Stop blaming the tubes...stop blaming the vendor....and focus on solving the real problem.

    "I know it's not going to happen but I wish someone would make a good quality tube...."

    The problem is not the tubes---the problem is you.

    Start your education here:
    http://drtube.com/en/modifications/jcm2000-stable-bias-mod

    http://www.marshallforum.com/threads/the-dsl-joey-mod-thread.13424/


    Read this and study it very carefully. You will be on the road to real progress.
     
    Last edited: Apr 21, 2017
  6. Neil Skene

    Neil Skene Active Member

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    The cathode resistor went almost as soon as it was taken off standby, no time to play. Didn't even get a chance to get the screwdriver in the slot to bring the bias up.
    I always back off the bias pots a little and start by taking the amp off standby with multi meter attached and bring the
    bias up to whatever I worked out from the previous plate voltage measurement. 490v in this case, I play for a while then check the plate voltage again on the new tube set and set the final bias.
     
  7. Neil Skene

    Neil Skene Active Member

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    Wow, Keep ya pants on!
    I have no test equipment so I try to buy tested tubes and hope they have been tested.
    The Vendor does not make the tubes and has accepted the return of the faulty set and has acknowledged there have
    been problems with these tubes from time to time so no one is blaming the vendor.
    I found the cause of the problem and fixed the damage it caused.
    I read the Joey Mod thread 5 years ago so you're a little late to the party on that one.
    I checked my board 5 years ago and found all the right value resistors are in my board.
    After I installed the Mercury PT, OT and choke I have no interest in any of the mods in that thread.
    My bias does not drift enough to worry about. I watch it every time I install new valves, I then
    check again after some hard use and it is always within 1ma of what I set it at, no problem.
    What's a real technician going to do for me during a simple valve change and bias?
    I have had this amp in it's current configuration since I bought it brand new with the speaker box about 12 years ago
    it simply plugs into the quad box 16Ω out put to 16Ω input no speakers blown no mods done no load problem, no tech needed.
    All tubes installed prior to this and now another 4 sets after I repaired it work perfectly. So (look out I'm about to do it)
    I assume the quartet has a faulty tube in it.
    You seem to have made a few assumptions of your own.
    You have quoted other peoples work and knowledge.
    Now, If you have anything constructive or helpful that actually comes from your own knowledge and work to add
    It may make you look a little less silly/nasty.
     
    Last edited: Apr 21, 2017
  8. AllanAnd

    AllanAnd New Member

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    Had a bad day, sir?

    Your impoliteness hurts me on behalf of OP.... It actually IS possible to make Your opinion known without mocking, so please try to...
     
  9. dslman

    dslman Well-Known Member

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    I had a brand new matched quad of TAD EL34Bs go bad within a month, could be coincidence, but it turned me off to them.
    Glad you were able to fix your amp.
     
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  10. Neil Skene

    Neil Skene Active Member

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    Thanks dslman.
    It was only a couple of resistors but the whole amp had to be pulled apart to get to them.
    I just bought a heap of NOS preamp valves but am still looking at the Kemper amps.
    I don't think I will buy another valve amp, not because of this but, it made me look at what else is now out there.
    I really think the future is going to be solid state modelers.
    By the time I buy another amp I think the the technology will be hard to walk past.
     
  11. NateSLC

    NateSLC Member

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    Hi Neil. I have never had anything like that happen and sorry that happened to you. The first thing that came to my mind wasn't that it happened but rather who you bought those tubes from? I don't think that you mentioned that and I was curious who the source of those tubes were.
     
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  12. SGed

    SGed Member

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    I can see from your photos, your DSL was made in 2004. You need to check the circuit board and verify if it is the revised one or the old one which had problems that could cause what happened.
     
  13. dslman

    dslman Well-Known Member

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    I think he said it was up to spec.
     
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  14. dslman

    dslman Well-Known Member

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    I hear ya, its a tangled web in the DSLs
     
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  15. MonstersOfTheMidway

    MonstersOfTheMidway Well-Known Member

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    @OP: I never had a brand new power tube(s) or a brand new preamp(s) fail on me, but I've certainly heard and seen such a thing happen to others elsewhere. It's unfortunate it happened to you, but believe me when I say you are not alone regarding this specific misfortune.

    Buying tubes that were tested was a good idea on your part, but I have a question: did the testing include a burn in? I know some dealers include a burn in with the testing procedure, yet some dealers do not include a burn in and consider it a separate service, which can add significantly add to the price of a new matched set of power tubes. I like to have my power tubes tested and burned in because I really want the dealer to be the one to suffer the tube failure, not me. I, probably like others here on this site, consider my time, money, and gear very important, so I try to do what I can to take as few risks as possible even though it might cost me a little money or time. I do believe you tried your best to do the same, but even then a tube might fail and sometimes take other out other components with the failure, as I've seen other suffer in the past.

    I also think that it's not paranoia or gullibility on your part to believe that a tube can fail and take out other components with it. A source that backs up this belief is the lack of return/exchange/refund policy some major brick and mortar stores adopt when it comes to the sale power tubes. Several Sam Ash in Southern California, for example, do not offer any return/exchange/refund on the power tubes they sell unless the power tubes are returned unused and in their original packaging. On different occasions and at different locations, I asked Sam Ash salesmen if they offer any guarantee against failure of their power tubes, and he said no. Most Sam Ash salesman have told me that I only get a factory warranty, and that it's up to the me, the customer, to contact the manufacturer (I also believe Sam Ash on line return/exchange/refund policy is similar in regards to the sale of power tubes). I gotta believe (thought I have absolutely no proof) that at the very least Sam Ash is aware of the various ways a power tube can fail; they might also have some statistics on the rate of failure for power tubes as well as other knowledge that guides their policies regarding the sale power tubes.

    On line dealers seem the better choice when buying power tubes mainly because most on line dealers offer some kind of direct guarantee in the form of a return/exchange/refund. Most on line dealers also offer testing and burn in, which I think is beneficial. And last, most on line dealers encourage communication between themselves and the customer, which can include a discussion of make, model, and year of your amp, the bias setting for new power tubes, and other playing conditions that might affects the life of new power tubes. But in the end, it's up to the consumer to research his/her options and try to make the best decision on what he/she buys, and where/from whom he/she buys.

    Glad to hear your amp is up and running again. Hopefully this never happens again to your amp. And yes, I, too, might be looking into an Axe-FX or Kemper in the future. Best of luck with your gear.
     
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  16. Ghostman

    Ghostman Well-Known Member

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    Ladies and Gentlemen,

    Our resident ****. :D Tactful as always.
     
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  17. SG~GUY

    SG~GUY Well-Known Member

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    -a lot of the vendor's that claim they burn the tubes in use no where near the plate voltage that your amp runs at.

    -well I hope tube amps never become obsolete, I'm betting that they never do, they claimed this would be the case in the 50's as well when transistor's became popular, supply and demand, if someone wants a product, someone will make and sell them, the new digital modelers like AXE & KEMPER are very, very impressive, but they'll be pulling my tubes and tube amps out of my dead dying, death grip, with full rig-a-mortis, in my other hand will be my empty COLT 357 PYTHON...
     
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  18. Gunner64

    Gunner64 Well-Known Member

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    I've had new tubes fail, with nothing being wrong with the amplifier. It's not always a doomsday scenario with the amp, new tubes can just go, just as easy as any component in the amp can..lets face it, tubes are the most delicate component in an amplifier.
     
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  19. Toby Krewbs

    Toby Krewbs Member

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    Its all part of being a tube amp player/ owner. I had my output tranny taken out by a shorted JJ years ago when I ran the amp hard as hell for two years without servicing it.That was on me and I knew it would happen.

    I have several nice modelers.They will never replace anything for me they are just generic tools like Harbor Freight carries. My Tube amps are Snap On and made for a player who wants to sound like himself.I will never give them up.
     
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  20. Jethro Rocker

    Jethro Rocker Well-Known Member

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    Could be. Might be some time. You can still buy and get processed color print, B&W and slide film. There are billions of old 35 film cameras around, some very good with nice glass for really cheap. Film technically is still around and so are tubes. Let's hope the tubes keep going!
     
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