Will it hurt my amp to play it with a dead power tube?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by gag halfrunt, Apr 8, 2015.

  1. gag halfrunt

    gag halfrunt A fellow of infinite jest Supporting Member

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    Someone just shipped me a 100 watt head, and one of the four 6L6 power tubes was dark when I fired it up. The other 3 all light up like normal inside. I'm assuming that means it's a dead tube. The amp sounded normal (tones seemed correct, no noise, squeals, static, or other odd sounds) when I tested it, but I'm worried I may damage the transformer by playing it. Does a dead tube in the mix change the impedance the power section wants to see from the speakers (like pulling a set of tubes would)?

    Anything else I should worry about? Should I play it safe and pull out the inner pair and run just the outer pair until I can get new tubes?
     
  2. Blue Strat

    Blue Strat Member

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    Try swapping sockets with it to see if the tube is really dead.

    Yes, using fewer tubes will change the impedance but not significantly enough to matter. If the tube really is dead, remove it.

    Using just 2 tubes is a good option. This doubles the load impedance that the amp wants to see.
     
  3. donnyjaguar

    donnyjaguar Member

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    I agree that running two tubes is probably the best temporary arrangement. You can also move your impedance selector (if so equipped) to the next value lower to "match" the cabinet to amp a little better = louder.
     
  4. doctorx

    doctorx Member

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    How about replacing the tube?
     
  5. zenas

    zenas Member

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    Now why would you want to do that ? :)
     
  6. schmidlin

    schmidlin Member

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    Lulz.
     
  7. gag halfrunt

    gag halfrunt A fellow of infinite jest Supporting Member

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    It will take a few days to get the new tubes shipped here. Just wanting to know if should avoid playing the amp until they arrive.
     
  8. big mike

    big mike Moderator - EL34 Emeritas Staff Member

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    Pull the outside pair.

    Leave a lit pair on the inside. 1/2 the impedance.
    As long as it's a fixed bias amp and not cathode bias.
     

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