200 hz hum in my garage.

Discussion in 'Amp Tech Center' started by ArcticWhite, May 12, 2020.

  1. ArcticWhite

    ArcticWhite Tele-Holic

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    [Just noticed I wrote 200hz in the title, instead 120. Gah! Wish I could edit that.]

    My house was built in the 50s.
    I have just one outlet in the garage. It is powered by an ungrounded cable, and has a GFCI outlet installed.

    I want to play in there, but my amp makes a loud 120hz buzz when I roll my guitar volume up.

    There's no buzz with the amp volume up and guitar plugged in. But as soon as the guitar volume is turned, up the buzz comes in with it.

    I've tried two different tube amps with the same result.

    There are ceiling lights in the house on the same circuit - several on dimmer switches - but the buzz persists even when they are turned off.

    I also have a garage door opener, and a microwave oven on the same circuit. Neither of these are running, obviously.

    Thoughts?
     
    Last edited: May 12, 2020
  2. Switchy

    Switchy Tele-Holic

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    But if any of your lights are fluorescent, even without a dimmer, they are a problem.
     
  3. ArcticWhite

    ArcticWhite Tele-Holic

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    All lights on the circuit are turned off.
     
  4. jhundt

    jhundt Doctor of Teleocity

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    what happens with a hum-bucker guitar?
     
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  5. Peegoo

    Peegoo Friend of Leo's

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    Plug in a long cable and walk around the room with the guitar. Does the buzz become more pronounced in certain parts of the room? If so, there's some EMI floating around there and you should be able to find the source.

    If not, the noise is getting into your signal via the AC mains supply. You can try a noise filter on your AC supply between the amp and the outlet.
     
  6. Switchy

    Switchy Tele-Holic

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    Do you windows in your garage, or are you playing with the door open? Where's the light coming from?
     
  7. ArcticWhite

    ArcticWhite Tele-Holic

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    Same thing.
    Still buzzes with guitar volume up.
     
  8. ArcticWhite

    ArcticWhite Tele-Holic

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    No difference. I can walk out the door and it still buzzes
     
  9. ArcticWhite

    ArcticWhite Tele-Holic

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    Windows.
    Nothing is on the circuit except for the clock on the microwave. It's built in, so I can't unplug it.
     
  10. Switchy

    Switchy Tele-Holic

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    You can use your guitar as a directional antenna, almost like a Geiger counter. I would see if the buzz is more pronounced in one direction or another. Maybe even track down the source.
     
  11. LPaulG

    LPaulG TDPRI Member

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    If the breaker box is also in garage start turning off breakers till you find it..

    and/or wire a new filtered circuit... I'd speculate it'either the circuit or the fluorescnts
     
  12. Old Deaf Roadie

    Old Deaf Roadie Tele-Afflicted Silver Supporter

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    What happens when you unplug the refrigerator? If there is a microwave, that puts the circuit in the kitchen. What else is on that circuit that you don't know about?
     
  13. jhundt

    jhundt Doctor of Teleocity

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    try moving to Boise...
     
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  14. ArcticWhite

    ArcticWhite Tele-Holic

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    The refrigerator is not on the circuit.

    The microwave is built in, and unplugging it would involve screwdrivers and heavy lifting - and for no reason, because it isn't turned on.

    I am not a fan of Boise. No offense.

    I may run a dedicated circuit in there. I need some more outlets anyway..
     
  15. Switchy

    Switchy Tele-Holic

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    The source of noise doesn't have to be on the same circuit.
     
  16. BigDaddyLH

    BigDaddyLH Tele Axpert Ad Free Member

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    Hmmm...



    Is that a G?
     
  17. RodeoTex

    RodeoTex Doctor of Teleocity

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    First I'd ask how you determined that it was a 120k hum.
    Secondly, is really suggest that you get a real electrician to check out your neutral and grounding service to the building.
     
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  18. edvard

    edvard Tele-Afflicted

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    You say your only outlet in the garage is ungrounded? Ground it before doing anything else; go to the hardware store and get an outlet tester (if you don't already have one) and an appropriate length solid copper wire. Run the wire from the ground connection at the outlet (if it has one; if it doesn't, replace it with one that does) to a clamp on a metal cold-water pipe, or to your house's ground stake if it's close, then test it with your tester. I'm not saying that's the cure-all, but it'll at least eliminate grounding as the problem, which it very well could be.
     
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  19. RodeoTex

    RodeoTex Doctor of Teleocity

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    Please don't try to ground an electrical circuit to a water pipe. Old school, not reliable, plus there is the problem of induced electrolysis among dissimilar metals doing this. Want to cause some water leaks too?

    Call a real electrician. Make sure he has an actual license. It really won't cost much for an evaluation.
     
  20. ArcticWhite

    ArcticWhite Tele-Holic

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    I'm confident it's a 120kh hum because I listened to a recorded one I found on a hifi website and they are identical in pitch.

    I'm not a licensed electrician, but I know how to run wire, add a circuit to a live box, etc. And I know that my ground and neutral are bonded in my main panel, and there is no secondary panel.

    There's an old motion detector that I noticed was on the circuit in my backyard. I haven't had a bulb in the fixture in years, but that's my suspect right now.
    I'll check it out tomorrow or when I get the time.
     
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