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Stop, hey, what's that (60 Hz) sound?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Testudo, Oct 30, 2004.

  1. Testudo

    Testudo Member

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    What exterior influences cause hum?

    I am playing in the spare room. The computer is off. The lights are off (and incandescent, anyway).

    Single coils into Emerald. Good cable. A ton of hum. I walk away from the amp. No effect.
    I turn 90 degrees. Significantly less hum.

    I can't figure this one out.
     
  2. saros141

    saros141 Guest

    For what it's worth...

    Could be the power lines and/or transformers in your area.

    In the 12th Fret you have to turn a certain way because the subway runs underneath.

    Sometimes the disturbance caused by high power transmission can extend pretty far away from it.
     
  3. Testudo

    Testudo Member

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    Excellent call, Saros, but in my case I doubt it. I live in a residential area with regular power lines about 150 feet from my amp. The nearest high-power lines are at least a mile away, and the only transformers are those little single-house ones on the poles. Who knows, though?
    Do you know much about house wiring? I'm at a loss when it comes to fancy stuff like power conditioners and the like. Could my house electrical be "dirty"?
     
  4. saros141

    saros141 Guest

    I don't know enough about house wiring and EMF to say anything definite, but I live on the 18th floor of a building (presumably distanced from the surrounding grid except my neighbors), and I have to pivot for the lowest noise too. I'm not too far from the elevators though.

    If the hum was always there and didn't change with position, I'd suspect the amp... if moving the guitar changes the hum (and turning down the volume knob kills it), then we have to figure out what's radiating it... the guitar is only an antenna. I would guess it's not the amp itself kicking off EMF because you say moving away while maintaining the same angular relationship doesn't help, which is the same situation for me...

    Anybody?
     
  5. Wakarusa

    Wakarusa Member

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    Have you checked over the guitar for bad grounds/shields?

    Experience the same hum with other single coil guitars?

    How do you know the cable is good?

    I'm assuming the amp is quiet with nothing plugged into it.
     
  6. LSchefman

    LSchefman Member

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    It's called "facing mecca", finding the no-hum spot in some locations when you play single coils.

    Your guitar is indeed, as someone pointed out, an antenna. Electromagnetic fields will cause what you're hearing. In my house, and studio, certain rooms are totally free of it, and others radiate EMI like crazy.

    F'rinstance...it hums near my circuit breaker box. It hums in the kitchen with the appliances*. It doesn't hum at all in my control room, despite the monitors, gear, etc.

    It's all about your house wiring, appliances, etc.

    * You're probably wondering, "Les, you have a studio, why would you play guitar in your kitchen?" And the answer is, "I was looking for someplace 'verby to record a guitar amp, and the kitchen has a tile floor and lots of glass windows."
     
  7. Testudo

    Testudo Member

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    Good ideas all.
    Yes. No faults
    Yes.
    Cable is good.
    Amp is quiet with nothing plugged into it.

    I think Les has hit it with "Facing Mecca".

    Maybe some kindly satellite would map the EMFs around my house so I could figure out where to play.
     
  8. tonedaddy

    tonedaddy Member

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    I am here as you are here as you are me and we are
  9. Testudo

    Testudo Member

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    Yeah, I gave up on worring about the voices years ago. I just think of them as little friends that are always good for a conversation.

    Back to the topic at hand - is the concensus that's building that there's nothing to be done? Just learn to stand the right direction?
    Or play only humbuckers...
     
  10. aeolian

    aeolian Member

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    Peter,

    You can try and improve the grounding in your house electrical system. Commercial instalations run the power though metal conduit which does provide some shielding although some of the junctions in the conduit don't have very low resistance, which leads to current flow, which leads to radiated noise. A house just has unshielded Romex although there is supposed to be a ground wire in there. By improving the overall ground for the house wiring, you improve the ability of the return line to drain away any extraneous noise it picks up from elsewhere. Big copper stakes driven way into the ground, connected to the electrical panel with braid are much better than a 14AWG wire to a water pipe. In my house, it was connected to the black iron gas main!

    You could always resort to putting copper mesh in the walls of your music room like we do in EMI labs. :D
     
  11. Testudo

    Testudo Member

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    Aeolian -
    Interesting. The house is newly wired with Romex and I am reasonably certain the contractor did ground it properly, as I know him and his work pretty well. I may give the copper stake plan a try. How far is "way" into the ground?
     
  12. Mark Robinson

    Mark Robinson Member

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    How large is the room? Try this, turn the axis of the amplifier 90 degrees and see if the optimum guitar angle changes too. Some amps have a pretty good sized field of transformer hum. I also had a bad run of hum caused by the proximity of a wah pedal, to a wall wart power supply on a pedal board. Good luck.
     
  13. Testudo

    Testudo Member

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    The room is roughly 12x12. I doubt it's the field from the amp because I can walk into the hall and hear it. But you've given me more things to search for. I think I will shut down everything electrical I can and see what happens. I'll try turning the amp, too!

    Oh, I forgot to mention earlier: the ceiling is 12 4-foot fluorescent tubes. Could that be part of the cause?








    Only kidding.
     
  14. Wakarusa

    Wakarusa Member

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    Way off topic here, but this is all covered in the building codes. In most cases your house has to have two ground paths. Lots of folks use one 6" stake (usually steel, not copper) and the water pipe. If you use two stakes they have to be something like 6' apart (it's been a while since I did this sorta stuff). There are rules on sizing the ground conductor too - usually a #8 or larger bare braided copper, almost never 14AWG ;)

    All that said, I'd be pretty surprised if mucking with the mains grounding scheme had any improvement on hum from EMI. The Faraday cage (mesh the walls, floor and ceiling) works like a charm, but gets expensive fast.
     
  15. Testudo

    Testudo Member

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    This copper mesh, where do I find it? I'm building a music room behind the garage, so now would be the time.
     

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