60 cycle hum

Discussion in 'Pickups & Electronics [BG]' started by wrench45us, Dec 17, 2012.


  1. wrench45us

    wrench45us

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    I have a newer bass with a single pole J pickup. I get a lot of 60 cycle hiss I'm trying to track down.(The P pickup is as quiet as can be.)

    I practice in a room with the family's wireless router. Since the whole purpose of that device seems to be to radiate an electromagenetic field, is this the likely source of my hiss?

    Or the computer, or DVR or halogen lamp or ???

    If I lay the guitar flat, the hiss goes away; it's worse when the pickup is vertical in playing position, but no better or worse facing one direction or another.
     
  2. Rune Bivrin

    Rune Bivrin Supporting Member

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    Move the bass closer to the suspect items. Stronger hum = probable source.
    Turn the suspect items off. Hum gone = probable source.
    Most likely is the transformer for the halogen lamp, but the source can really be anything mains powered.
     
  3. eriky4003

    eriky4003

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    Is it hum or hiss?
    I had a 60 Hz hum at a gig and then I started to notice it at our rehearsal room. Purchased an ElectroHarmonix Hum Debugger and it works extremely well by eliminating about 95% of the hum.
     
  4. wrench45us

    wrench45us

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    It may very well be 60 Hz hum
    There's no noise at all with the P pickup and touching the strings doesn't eliminate the noise, so it's not a grounding problem, so I'm thinking its all the single pole J pickup sensitivity.

    I'll look into the Hum Debugger.
    Thanks
     
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  6. line6man

    line6man

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    These things do not produce any emissions in the audio frequency range. Definitely no 60Hz content or the nearby harmonics of 60Hz, either way.

    Unless you have an old-fashioned CRT based computer monitor?
     
  7. wrench45us

    wrench45us

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    There is a cathode Ray tube 32 inch TV that we're waiting patiently to die to replace it with a flat screen.

    Based on your criteria that could be the source.

    so much for practicing with the TV on and the sound turned down?

    would the Hum Debugger address this, if it is the TV/
     
  8. Steveaux

    Steveaux

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    Turn the TV off and unplug it.
     
  9. line6man

    line6man

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    I don't know how well those things work. The problem with 60Hz hum and other offending electrical field frequencies is that the only way to get rid of them is to cancel out with an identical signal at a 180 degree phase difference. This is very difficult and impractical. The common method to reduce hum is to apply parametric EQ of very narrow bandwidth to reduce the volume of the offending frequency and nearby harmonics. The problem is, you either apply too little EQ and still hear the hum/its harmonics, or, you apply too much EQ, and it compromises your sound. Also common is the use of noise gating, which silences your output when the signal drops below a certain threshold. What this means is that you will be silent when you are not playing, but when you do start to play, the hum comes through, and you hope that your playing "hides" it. The effectiveness of either method seems to depend largely upon the specifics of the application. In some cases, either method will work great, but in other cases, either method will not be effective.
     
  10. wrench45us

    wrench45us

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    I suspect it is an 'instant on' TV so just turning it off will not render it 'silent'
    so unplugging would be the true test

    thanks all
    I have some fairly simple experiments to try this evening
    \
     
  11. wrench45us

    wrench45us

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    What I've found.
    --There is no discernible source per TV or halogen light or computer, but in the room the noise is very directional. Within 5 degrees 180 apart there's no noise.
    --Different plugs in the room make no difference.
    --The nearest socket outside the room makes no difference.
    --Across that room, on the opposite wall all the noise completely gone.

    This whole section of the house was remodeled in the 80's, including the socket across the next room that's noiseless.

    Something about the quality of the power in this part of the house???
    Unfortunately my compact home studio is set up in the first noisy power room.
     
  12. joelb79

    joelb79 Supporting Member

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    Computers in the same room are noise central. Even my EMG's can pickup hum and whine my computer at the right angle, especially if they are close enough to the harddrive. you can actually pickup the spin of the drive with guitar pickups because the moving metal parts make enough magnetic field to create whine.
     
  13. Joe Louvar

    Joe Louvar

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    If everything is correctly wired, well shielded and grounded and the noise is coming from the bridge J pickup and not the neck P pickup, you may need to replace the bridge J pickup with a noiseless type pup to reduce the noise.
     
  14. Crater

    Crater

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    I had very similar symptoms to what you describe. 60 Hz hum from my single-coil guitars, the hum was quite directional, but would be at a minimum if I faced towards the "null point". I eventually found out that all of the outlets in our rented house were UNGROUNDED in spite of being 3-prong outlets. I intended to install a separate ground wire, but never did and we moved out of that house last year.

    We moved into a house with actual grounded outlets, my single-coil pickups are MUCH quieter now. This whole section of the house was remodeled in the 80's, including the socket across the next room that's noiseless.

    Check the outlets with one of those "outlet testers" from your local home improvement store, they're about $5 or less.
     
  15. wrench45us

    wrench45us

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    ungrounded outlets seems the most likely explanation
    all equipment was off in the original room when I was 'testing'

    there's been some peculiar behavior of some electronics that may also point to no actual ground -- like computer and TV turning on when lost power is restored even though they weren't set to on
     
  16. SGD Lutherie

    SGD Lutherie Banned

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    Single coil pickups hum. The P is a humbucker.

    The rest of the noise is from things like computers and light dimmers. Shielding can help, but some of those kinds of noise are hard to get rid of.
     
  17. wrench45us

    wrench45us

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    thanks to enough walking around experiments, the evidence is pointing to ungrounded outlets, as I found at least one outlet that eliminated the noise I was hearing
     
  18. Meddle

    Meddle

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    Does the EHX hum debugger work as a very narrow notch filter, or does it actually contain a 60 Hz oscillator tuned 180 out of phase with the mains or what? I've heard criticism of it, as a pedal. Also, surely the UK version must be different from the US version as we run different power systems? Same with mainland Europe...
     
  19. wcriley

    wcriley

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    That's interesting because I didn't think the lack of a safety ground would affect the EMI picked up by pickups or other electronic devices.

    I've worked in quite a few older venues that didn't have grounded outlets and never noticed an increase in hum.
     
  20. SGD Lutherie

    SGD Lutherie Banned

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    I guess if the outlet ground is missing the noise picked up on the power lines doesn't get shunted to ground.
     
  21. wcriley

    wcriley

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    How would that affect the airborn EMI in the room, as seems to be the case here?

    Not being argumentative. Trying to understand and (hopefully) learn.
     

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