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Will badly biased tubes take out an OT?

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  • Will badly biased tubes take out an OT?

    This kid has a DSL50 50W 2EL34 amp, with one tube drawing 27ma and the other drawing 50ma. Somebody was obviously playing with the bias pots. The OT died. Would this possibly cause the OT to die? The tube that was drawing 50ma looked pretty cooked.

  • #2
    Probably not.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      I've had a red plating tube create a short across the OT primary, so yes, it's possible. Peter.
      My band:- http://www.youtube.com/user/RedwingBand

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      • #4
        Originally posted by pdf64 View Post
        I've had a red plating tube create a short across the OT primary, so yes, it's possible. Peter.
        There's a HUGE difference in current draw between a red-plated EL34 and one that is drawing 50mA. It is unlikely that this scenario per se caused the OT to fail.

        On the contrary, a failing OT COULD cause the difference in cathode current readings. So it's really a case of the-chicken-and-the-egg here.
        John R. Frondelli
        dBm Pro Audio Services, New York, NY

        "Mediocre is the new 'Good' "

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        • #5
          In this case, someone had tweaked one of the bias pots way out of whack. It was possible to get them to pull similar amounts of current with the pots set at about the same level. But the OT was already messed up at that point. I was just curious about the possible results of having the tubes biased that far apart.

          Thanks everyone, for your replies.

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