Please help me diagnose this amp noise...

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by evanjackson, Dec 14, 2005.


  1. evanjackson

    evanjackson Supporting Member

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    Sometimes, my amp will make this soft crackling sound...the best way I could describe it is it sounds kind of like the noise you here when someone is, say, handling a microphone and you hear the incidental noise that gets transferred...it's very soft, and seems independent of volume. Any ideas? Thanks!
     
  2. axolotls

    axolotls Guest

    my amp does this too, and i cant seem to locate the origination. so i would like to know too. it seems to die down after the amp warms up.
     
  3. donnyjaguar

    donnyjaguar Member

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    I repaired an old Danelectro with the same noise you describe. This was an easy problem to fix - one of the tube sockets was dirty. Try wiggling the tube within the socket (in standby) and see if it affects the sound.

    The other culprit for this sound is a resistor (usually plate) that has gone bad. In my experience these resistors can be way out of tolerance and the voltage ampliifer will still be working. A voltmeter is your friend for testing here.
     
  4. SteveVHT

    SteveVHT Member

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    More than likely a bad Phase Inverter tube.
    Steve
     
  5. 1-Take-Wonder

    1-Take-Wonder Member

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    what have you done already?

    +1 on tubes, standard tube amp troubleshooting (especially with random noises) is check/replace the tubes, usually starting with power, and then pre-

    curious SteveVHT, why did you go to the phase inverter? Always looking to learn more about diagnosing problems quicker!!
     
  6. bob-i

    bob-i Member

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    You don't mention what type of amp this is.

    I'd suspect PI tube or power tube, or connection to these tubes, since it's independant of volume.
     
  7. Richard Guy

    Richard Guy Member

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    Don't rule out the computer that is in the house. Try turning it off and see what happens.
     
  8. evanjackson

    evanjackson Supporting Member

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    Thank all of you for your help...the amp's a reverend hellhound and it could very well be the tubes (haven't retubed in a while) so I'll check that out. It seems like it's usually the tubes that are the problem
    Thanks again!
     

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