Tube in Amp Glowing. why?

Discussion in 'Amps and Cabs' started by presvis20, Feb 18, 2012.

  1. presvis20

    presvis20 Member

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    Hi
    My h&k statesman makes a weird microphonic noise and when i saw the tubes one of them is acting weird. Why , some pointers please. And if i change the tubes how can i bias my amp?
     
  2. Blackmoreguitar

    Blackmoreguitar Supporting Member

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    Can you be a bit more specific. How is it acting weirdly and which tube is it? Is it a power tube or peamp tube?
     
  3. presvis20

    presvis20 Member

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    Its a quad el84 amp. And one of the power amp tubes is over glowing making a weird noise.
     
  4. presvis20

    presvis20 Member

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    I should change all the tubes right? not just the one.
     
  5. Blackmoreguitar

    Blackmoreguitar Supporting Member

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    The first thing I would do is swap the weird acting tube with one of the other ones. If the tube is still acting strangely when moved to a different position then you know that it is a faulty tube. If the weird glow stays in the same position and does not follow with the tube then the amp has a fault. Assuming it is the tubes then yes I would recommend getting a matched quad and replacing all of them. The Statesman does have easily accessible biasing points and bias trimeer (I just looked at the manual) so I would do the biasing myself, but if you are not comfortable you need to take it in.
     
  6. presvis20

    presvis20 Member

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    ok man thank you. What happens if i dont bias the amp? And how do you bias the amp exactly? I just bought the amp and i have any money left so..... especially if i take the amp to a technician...
     
  7. PlinytheWelder

    PlinytheWelder Member

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  8. JoeP

    JoeP Member

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    EL 84 you don't have to bias. Just change them and your set, if it's tube problems that are giving you the trouble.
     
  9. PlinytheWelder

    PlinytheWelder Member

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    The H&K Statesman seem to have external bias pots and measuring points (a good idea IMO) so it should be easily biased with a DMM.

    A lot of EL84 amps are cathode biased and you can just dump new tubes in, but not this one.
     
  10. ken374

    ken374 Member

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    sounds like red plating, change tube
     

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