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Redhead blown Preamp tube?

Discussion in 'Amps and Cabs [BG]' started by Rusty the Scoob, Mar 11, 2009.


  1. My beloved Redhead gave me the first hint of a problem in many years of heavy abuse last weekend. Someone had bumped the Fan switch to off so it overheated at the end of the night and went into thermal shutdown.... which also kills the DI, incidentally... not good.

    So after it cooled back down I was able to turn it back on and hoped everything was ok. The next morning I plugged a bass into it and it works, but now with a hint of distortion added to the sound, regardless of what volume setting I use. I tried an extension speaker with the internal speakers turned off, so it's not a blown driver or tweeter.

    Does this sound like a partially bad preamp tube? (I'm hoping so!) The tube is over 7 years old and it's been used quite a bit during that time.
     
  2. Try changing the tube but I suspect that the overheating has caused some damage.

    Paul
     
  3. That isn't a terribly long life for a preamp tube, abused or otherwise.

    But if you have any other preamp tubes on hand, a quick swap will show you if there are any issues. However, the fan will be there more to keep the rest of the amplifier cool, exterior convection cooling isnt going to change the temperature of the tube much as it has an internal heating element.

    Still, try a tube swap anyway, see if it helps. Just hope it isnt thermal damage to anything else on the PCB :(
     
  4. KeithPas

    KeithPas Supporting Member

    May 16, 2000
    Poulsbo,Wa
    Did you try more than one bass the next morning? I know it sounds pedestrian but I would rule out the bass itself (if it has batteries) as well as try another preamp tube.
     
  5. Good thought, Keith. Yes, I tried two basses and at least one of them sounds fine through a different amp.

    I'll definitely try the tube swap but won't have time until Saturday or so... the suspense is killing me!
     
  6. KeithPas

    KeithPas Supporting Member

    May 16, 2000
    Poulsbo,Wa
    Good luck!!
     

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