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Power Tube Lifespan?

Discussion in 'Amps and Cabs [BG]' started by smogg, Oct 29, 2018.


  1. smogg

    smogg

    Mar 27, 2007
    NPR, Florida
    I'm not crazy, I'm just a little unwell
    Need input from the collective please. One of the guitarists in my current band claims his "tech" said he needs to change out the power tubes in his amp every two years. For some reason that doesn't sound right to me. Could he have meant re-bias every two years? What say you tube amp gurus?
     
  2. rickdog

    rickdog Gold Supporting Member

    Mar 27, 2010
    Personally, I wouldn't change tubes based on the calendar. I really don't think you can predict tube lifetime very well with current production tubes. They really don't make them like they used to.

    But if your guitarist has been bringing the same amp to the same tech for years, maybe the tech has enough history to look at that he can predict that a two-year replacement cycle is about right to ensure trouble-free operation. So I wouldn't dismiss the idea completely. But I hope the tech is at least testing the tubes before replacing perfectly good ones. ;)
     
    smogg likes this.
  3. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Change power tubes when there is a measurable decline in either tone or output power. Changing them just because invites the inevitable damage, or a defective new tube experience.
     
  4. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    100% agreed. The power tubes in my B-15 have been in it for 10 years now, in my SVT and V4B for over 5, and up until about 3 years ago, my 73 Super Reverb had the same power tubes it came stock with.

    This used to be true. I'm not convinced it is anymore. Some of these new tubes have amazed me with their longevity. The stock Sovtek tube in my REDDI has lasted over 6 years now, and I use it pretty regularly.
     
    smogg likes this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Since I do have a lot of experience with new manufacture tubes, there are some very reliable tubes being made (JJ ECC83 is one, the Ruby 12AX7AC5 is another) but identical tubes may show different reliability metrics in different applications. I have a few designs that I've calculated 80% of the tubes should well last past the 10k hour mark and maybe 50% all the way to 20k-30k hours. There are also designs that are notoriously hard on tubes.
     
    JGbassman, smogg and JimmyM like this.
  6. BogeyBass

    BogeyBass

    Sep 14, 2010
    Ratings will depend on tube type, amplifier design and actual hours of use.

    Russians have different tube ratings.
    Related to quality, longevity and ruggedness.

    A tube being run at max ratings would assume to have less life.
    Likewise a tube being run at max ratings, but minimal run time or hours could last longer. Likewise a tube being exposed to big temperature changes. Or rough loading or vibrations could potentially reduce average lifetime

    Likewise same thing with tube being run at minimal ratings. Assume last longer. But heavy vibrations and rough handle or long operating hours can still reduce that.

    Assume 3,000 to 10,000 hours
    And 6,500 hours being the median

    Some tubes last 20 mins lol some last 20years. Minimal hours, maybe sound like krap. But yes they still work.

    Spacers and plates and heaters suspended close to cathodes. Heck sitting on a shelf they last pretty good. In the field Things work loose and rattle around. Plenty ping ding microphonic rattle buckets in a matter of time...all depends
     
    Last edited: Oct 29, 2018
    smogg likes this.
  7. rickdog

    rickdog Gold Supporting Member

    Mar 27, 2010
    I should have directed my remarks about tube lifetime specifically towards power tubes. I had two premature failures of Tung-Sol reissue 6550s out of a set I bought for my SVT a few years ago. Other people have had good results with the same tubes in the same amp, so I'm thinking I just got tubes that were made on a Monday or Friday.

    My JJ preamp tubes and EL84s in my CTM-30 are doing great, I use that amp a lot, routinely pushing it hard.
     
    smogg likes this.
  8. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    A good argument for paying a little extra for a 24 hr burn-in :D
     
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  9. rickdog

    rickdog Gold Supporting Member

    Mar 27, 2010
    Well, those Tung-Sols lasted for quite a bit more than 24 hours... but they were still very easy hours of home practice levels and very few gigs.
     
  10. primusfan1989

    primusfan1989

    Jan 17, 2005
    new jersey
    It really depends, like someone who does 250 gigs a year is going to need to replace tubes much sooner than a weekend warrior. Certain circuits will chew threw tubes and some don't. NOS GE tubes are gonna last longer than lower end Chinese modern production tubes.
    Personally I have my amp gone over every 100 hours, replace tubes as needed
     
    smogg likes this.
  11. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    It’s possible that the tech is recommending changing the tubes as a preventative measure for a giging amp to ensure that it won’t go down during a show. And, in a fixed bias amp, the bias should checked as part of a regular maintenance schedule. At least once a year if an amp in regular service.

    A tech for a touring band might change the tubes more often than they need to when cost isn’t an issue. Some do it every so many hours of service or before an amp is used for recording. If line power varies from venue to venue, bias will be checked before each show.

    Tube life depends on the amp design, the type of tubes, and how hard it is driven.
     
    Last edited: Oct 30, 2018
    smogg likes this.
  12. 707GK

    707GK

    Jun 13, 2013
    Northern California
    I use me ears and not a calendar to determine when to replace tubes, both preamp and power amp.

    And as was mentioned, it depends on a lot. The design of the amp, how hard you push the amp, how often you play, etc.

    I try to practice 30-60 minutes a day, I have 2-4 hour full band rehearsals sometimes twice a week, sometimes twice a month depending on schedules and I gig multiple times a month depending on a variety of things. With this schedule, I have only needed to replace my power tubes once, just last month, after about 5 years of using this amp exclusively. The preamp on my amp seems real hot, fragile, and uses an ECC832, for some reason that tube goes out on me every 2 years or so.

    The preamp tube in my amp makes a distinct popping noise when it is on the way out and the amp starts to seem quiet, needing re-biasing every 2-3 weeks, when the power tubes start to go. But this is just my limited experience with my amp, bass, playing style, and schedule.
     
    smogg likes this.

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