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Tube Lifespan?

Discussion in 'Amp Input - Normal or Bright' started by AndyFroncioni, Feb 4, 2018.

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  1. AndyFroncioni

    AndyFroncioni Strat-Talker

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    I have a Blues Jr III (EL84 tubes) and I'm wondering what I can do to care for the tubes in it? What shortens their lifespan? How many operating hours can I expect from them?
     
  2. heltershelton

    heltershelton BANNED Strat-Talk Supporter

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    man, thats a hard question to answer.
    turning the amp on and off several times a day is bad.....thats why they invented the standby.
    it depends on how often you use the amp, how loud you play, how bumpy the ride is taking to from here to there and back.....all kinds of stuff.
    i guess you could google, "how long do el84 tubes last" and research it a little to get a better answer.
     
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  3. AndyFroncioni

    AndyFroncioni Strat-Talker

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    I should have asked: what are the factors that shorten EL84 tube lifespan?

    Should I leave the amp on during the day, if I'm going to play it a few times? Should I keep the tubes cool by using a fan?
     
  4. jstewart

    jstewart Strat-O-Master

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    Tubes can last from a few seconds to years. It’s a crapshoot. Don’t worry about. They are inexpensive and easy to replace.
     
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  5. fezz parka

    fezz parka Strat-Talk Supporter

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    Not much. Be nice to the amp, they'll be nice to you.

    Red plating. Running a cab that's less than the load it wants to see. Example: amp wants to see 8 ohm load, you run it at 2 .

    Depends on the tube.
     
  6. heltershelton

    heltershelton BANNED Strat-Talk Supporter

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    well, you DID ask that...everything shortens their life. its kinda like "the day you are born is the day you start to die".
    concerning leaving it on all day.....i would leave it on if you were going to go away for an hour or so then come back, but if it was the early morning and you left and werent going to come back until the evening you should probably turn it off.
    as far as fans go....some people have small fans built into their tube amps to help move air.....there was one built into a marshall i used to have.
    but tubes are better when theyre hot, so you dont want to cool them off TOO much.
     
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  7. Stratoholic

    Stratoholic Senior Stratmaster

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    I do have somewhat limited experience with tubes, I've only had 3 tube amps in my life. But I can say that sometimes tubes might give you a warning before they're about to go. If one is about to stop working, you might get odd buzzing, pops and crackles, or the sound might cut in and out. Or, you get no warning, one day, you'll turn on your amp, the light will come on like normal, and you get very little to no sound at all from the speaker.

    Since you have a Blues Jr, the bias is fixed, so you don't have to go and adjust it or have it adjusted every time you change tubes, all you need is a matched set, pull the old ones out, and put the new ones in, and you're good to go.

    Oh, and don't move the amp around when the amp is on, or for a while after you turn it off. You could damage the tubes if the amp is moved around while they're hot.
     
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  8. 8T_BoCO

    8T_BoCO Aspiring Stratospheric Stratitician

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    I'd have a spare set of tubes around, because they can fail without warning. As for longevity, I agree with what's been said above - it depends.
    Generally, I'd say output tubes take more of a beating than input tubes.
     
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  9. fezz parka

    fezz parka Strat-Talk Supporter

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    That's not how it works brother.

    Fixed bias is set at a fixed point. Even though Fender doesn't tell you, there's a mod to add a trim pot to set the bias.This should be checked when swapping power tubes. Cathode biased amps are plug and play to a certain extent.

    From the late Bill M.

    http://billmaudio.com/wp/?page_id=1155
     
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  10. candyapple1964

    candyapple1964 Senior Stratmaster

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    Unfortunately there is a mixture of terms that leads to confusion.

    Cathode biased- the circuit is designed such that the operation range of the tube and its bias is found by reaching an equilibrium. The bias point is reached automatically. The tubes run hotter and won't yield as much power as other bias methods. The most unfortunate thing is its also known as fixed bias because you can swap tubes with no need to adjust!!

    Then there is the type of circuit fender uses in its more modern tube amps. The bias needs to be set. In factory for many amp models they will arrive at a compromise and use power tubes that are selected to work with the circuit. The bias is not fixed at all. Its just that there is no trim pot to adjust it. Its fallen in to common use to refere to an amp with no trim pot fixed bias when in fact it should be called "inconvenient to adjust but still required" bias.
     
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  11. fezz parka

    fezz parka Strat-Talk Supporter

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  12. RJ Squirrel

    RJ Squirrel Senior Stratmaster

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    As previously mentioned, avoid turning the amp on and off needlessly. The glass envelopes and internal components expand and contract at different rates. Also, allow the amp to cool down before moving it. Tubes are more susceptible to damage when they are hot. Here's an interesting read that provides an in depth discussion on the subject.
    http://tubebooks.org/Books/Atwood/Tomer 1960 Getting the Most Out of Vacuum Tubes.pdf

    Something else that is your control is tube selection and vendor selection.

    Some EL84s are more rugged than others. IMO, the most rugged EL84 type tube available is one of the Soviet military surplus 6n14n variants. The 6n14n is a 3,000 hour tube rated for 14 watts plate dissipation at much higher voltages than the current crop of new production el84's. The 6n14n-EB is a 5,000 hour tube.
    https://www.hobbielektronika.hu/forum/getfile.php?id=21127

    Some vendors have a burn in process before matching. Others do not. The burn in process is useful to weed out culls and to allow the current draw of the tubes to stabilize before matching.
     
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  13. Stratoskater

    Stratoskater Fuzz Meister General Strat-Talk Supporter

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    I find kicking them shortens the lifespan.
     
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  14. johnthomas

    johnthomas Strat-Talker

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    hi Andy Froncioni,
    With a Blues Jr Tweed version which got played about 2 hours per day, I got about 1 year before a 12ax7 went sort of microphonic.
    I replaced all 5 tubes at that time with JJ's and there was a pleasant modest improvement in overall tone.
    Buy some fuses ( like maybe 5 )
    to keep on hand as well as a backup set of tubes. I suspect you can do better than a year with no worries. I think I moved mine while the tubes were a little hot, so did not get maximum usage. Do not worry about the lack of a standby switch.
    Play that puppy!
     
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  15. Robins

    Robins Dr. von Loudster Strat-Talk Supporter

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    Run a tube amp at bedroom level of volume - decades to go if nothing bad happens to the tubes.
    Run it open every day and it will eat tubes like nothing.
    Of course heat is every tubes foe (like "hot tubes") and a hammer.

    All the best,
    Robin
     
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  16. AndyFroncioni

    AndyFroncioni Strat-Talker

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    What if I turn the Master knob to full all the time, but keep the Volume knob at low to keep it at bedroom level? Does that mean I'm heating up the EL84s more than normal?
     
  17. Borgatomic

    Borgatomic Strat-Talker

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    I'm still using tubes that are older than I am, and I'm old.
     
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  18. Kstu

    Kstu Strat-O-Master

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    I'm not sure they're guaranteed any amount of time. The JJ el84s in my Vox went out and I don't move the amp at all. I think they lasted 4 months maybe and I don't use it a lot as I bounce around using different amps. I put the inexpensive tubes it came with back in and so far they outlasted the upgraded tubes. When their time is up, it's up.
     
  19. gibsonsmu

    gibsonsmu Senior Stratmaster

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    They are basically a more rugged derivative of a light bulb. That's the way I think about em. There are things like redplating and hot biasing that will wear em out fast or even destroy them but you are more likely to sell that amp than you are to have a power tube problem. Most amps I have bought have had the original tubes. Point is I wouldn't sweat it too hard
     
  20. Silvercrow

    Silvercrow Senior Stratmaster

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    Can't verify the veracity of this, but a good friend had a Mesa F30, EL84's, in a combo amp. He claimed he ran through tubes like mad because of the vibration / proximity of the tubes to speakers (rear). He contacted a guy who was making something called a "Tube Tamer" for Peavey style amps in order to help with this. The guy made my friend one for his F30 (two EL84 tube). Nothing more than a channeled "bar" with springs on either end, held the tubes firm to the sockets / chassis.

    He claimed from the day he started using it his tube life lengthened significantly.

    Again- can't verify personally, but it would stand to reason that excess vibration and hot tubes= potential tube failure.

    Best wishes!

    Brian
     
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