What is the name for these tube problems?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by express75, Jun 4, 2008.

  1. express75

    express75 Member

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    1. I play a note it sounds correct but then fades with a litte fizzle into silence. It seems to get better as the amp warms up.
    2. Whenever I play a D cord or a single D note the amp takes off into crazy feed back and high pitch squeal.
    3. The tube has a florescent purple/blue small circle on each side of it.

    Yes I replaced the tube and that fixed it. Is there a technical name for these problems other than just saying it was a bad tube.
     
  2. Blue Strat

    Blue Strat Member

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    Sounds like a microphonic tube (#2) that glows blue.

    Technically, if it's still amplifying (you still get sound from it) it's not "bad". It's just unusable in your particular application.
     
  3. express75

    express75 Member

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    It is a brand new JJ 6v6. Maybe 10 hrs on it. I hear Key words like microphonic, red plating and gassy tubes(?) and wondered what applied to me so I could do a search.
     
  4. VikingAmps

    VikingAmps Member

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    I've seen a lot of failures of new production tubes lately. Your best bet is to get NOS from a reputable dealer that tests them thoroughly if you want to cut down or eliminate premature tube failures.
     
  5. express75

    express75 Member

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    I will give Blue Strat a call.

    Thanks
     
  6. express75

    express75 Member

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    RedMan is a good chew.
     

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