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Drri has a wierd screeching noise

Discussion in 'Amp Central Station' started by PeterVV, Jul 31, 2015.

  1. PeterVV

    PeterVV Tele-Afflicted

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    When warmed up the amp has a wierd faint screechy / whistle type sound. Doesn't get louder when you turn the volume up,. But stays there when the volume is off.
    Any ideas?
     
  2. Tony474

    Tony474 Poster Extraordinaire Platinum Supporter

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    Is the sound actually coming from the speaker or could it perhaps be some internal component such as a valve physically vibrating (ringing) at a high frequency?
     
  3. uriah1

    uriah1 Telefied Gold Supporter

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    Sounds like a bad PI tube going?
    Did you tap some of the tubes?
     
  4. BobbyZ

    BobbyZ Doctor of Teleocity

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    Unplug the all the reverb and footswitch and try it. If that isn't it pull V1 and try it in V6. Not it? Stick old tube back in and keep trying it.

    If you have a spare 12ax7 just use that to leep frog through the preamp tubes. Or a 12at7 just so it's good.
     
  5. PeterVV

    PeterVV Tele-Afflicted

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    It does seem to be coming from the speaker. V1 and v2 pass the tap test
     
  6. majorbugout

    majorbugout Tele-Meister

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    I've had this sort of thing happen when filter caps start to fail.
     
  7. Platefire

    Platefire Friend of Leo's

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    First things first. Try plugging the amp in a different electrical outlet. Plug your guitar in the amp direct without any effects and if you have an extra guitar---try a different guitar and/or with a different cord. Try turning your cell phone off and see it it goes away. My cell phone makes all kinds of noise around my amps. Try plugging into the normal channel to see if you have the same thing? If it's channel specific, I would try another preamp tube for the offending channel. Check tubes first by replacing one by one with a known good tube(as already previously said). Once all tubes have been checked and problem persist, it may be time to look inside. Platefire
     
  8. Wally

    Wally Telefied Ad Free Member

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    +1 on the cellphone thing.
    Pull tubes...starting on the right as you look at the back of the amp. If and when you pull a tube and the noise goes away, you have found the area of concern. If you pull all tubes without the noise going away,that is informative also. Let us know what you find.
     
  9. uriah1

    uriah1 Telefied Gold Supporter

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    True cell phone by pedal or amp not good
     
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