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Rustling noise when amp is idle

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by funkywrench, May 16, 2011.

  1. funkywrench

    funkywrench Member

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    I have recently picked up an Orange Rocker 30 and I've been trying some preamp tube swaps lately.

    I noticed when I was playing last night that during idle the amp makes a rustling noise on occassion. It goes away when I start playing (or perhaps it can't be heard over the playing, I don't know). It doesn't go away even with the guitar volume turned down. It will go away when I switch the amp to standby though.

    I don't think it was making that noise prior to the tube swap but I'm not 100% sure about that.

    Could I have possibly swapped in a microphonic preamp tube? What could cause this rustling noise?
     
  2. cvaldeski

    cvaldeski Member

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    maybe dirty tube socket(s)?
     
  3. Cthross

    Cthross Member

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    Sometimes bad cables can cause a rustling noise. I've noticed this happen to guitar cables and power cables between amp heads and cabinets.
     
  4. Blue Strat

    Blue Strat Member

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    Disconnect everything from the input jack. Still make noise?

    Very likely one of your new preamp tubes. ALWAYS suspect the last thing that changed.
     
  5. twangbanger

    twangbanger Member

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    :agree Hey this is my 1000 post!
     
  6. rob2001

    rob2001 Member

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    What else might cause this besides tubes? My JCM 800 does this and I know it's not the tubes.
     
  7. Blue Strat

    Blue Strat Member

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    Plate load resistors on the preamp tubes would be at the top of the list...also anything in the signal path.

    Do any of the controls affect the level of the noise?

    Did you check the preamp tubes in another amp?
     
  8. rob2001

    rob2001 Member

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    It's been doing it for years thru several tube changes. It generally doesn't bother me unless i'm recording. I guess I never checked to see if the controls affect the noise. It makes the noise with nothing plugged into it.
     
  9. Blue Strat

    Blue Strat Member

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    Try the controls...it might help localize the problem.
     
  10. thiessen3.14

    thiessen3.14 Member

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    i just went through my (new to me) old princeton reverb trying to find a "rustling" noise. cleaned all the pots/jacks, cleaned them again. checked the signal path--everything looked great. eventually got down to the speaker and found a cold solder joint on one of the speaker terminals. easy thing to check in addition to the above items.
     
  11. donnyjaguar

    donnyjaguar Member

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    Like Bluestrat says, check the plate resistors. These can be wildly out of specification and the amp will still play. Very easy to test with ohmmeter while amp is off, unplugged and discharged.
     
  12. Blue Strat

    Blue Strat Member

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    ...and they don't have to be out of spec at all to be noisy. If you can pin it down to particular stage, replacing the resistors is the quickest way to find out if they're causing problems.
     
  13. kurtsstuff

    kurtsstuff Member

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    My experience is..99.99.99% of the time it's a cold solder joint
     
  14. donnyjaguar

    donnyjaguar Member

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    Usually the cold solder joints respond to whacking the amp when its on. :)
     
  15. Blue Strat

    Blue Strat Member

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    "Percussive maintenance". :D
     
  16. mxvin

    mxvin Member

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    Thas how my Dad used to fix the TV set.....:bonk
     
  17. Blue Strat

    Blue Strat Member

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    I'll bet it even worked sometimes. :)
     
  18. LPMojoGL

    LPMojoGL Music Room Superstar Supporting Member

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    Is that like "pillow therapy" in the healthcare field?
     
  19. Blue Strat

    Blue Strat Member

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    In the sense that they're both "catchy" phrases, yes they're alike. :)
     

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