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The kind of hum that changes depending on where you stand...

Discussion in 'Pickups & Electronics [BG]' started by Gremson, Dec 4, 2018.

  1. Gremson


    Mar 22, 2012
    North-Leftern USA
    I know the TB folks really encourage the search function, but I don't even know how to put it into searchable words. All I come up with is ground hum.
    But I've got the kind of hum that goes away if I hold my bass juuuust right in proportion to my amp. When it is in position it's dead silent, and I've already lined the beasty with copper tape. I don't have any ground issues. But how do I solve this perfect placement hum issue?
    It's a 70's Epi ET-280 with original pickups. Are my pickups just worn and tired? Are there any fixes other than finding the perfect place to stand at each gig?
  2. ctmullins

    ctmullins fueled by beer and coconut Gold Supporting Member

    Apr 18, 2008
    MS Gulf Coast
    I'm highly opinionated and extremely self-assured
    Is your copper tape connected to ground? Check with a multimeter. Also could need some shielding in the pickups/cavities.
  3. This could be your pickups, picking up (huh) electromagnetic waves from other sources of electronic/electrical equipment. All electronic/electrical equipment radiate EM waves in some form or another and to some degree or another. That FCC notice on the back of, or in the manual for electrical/electronic equipment is what this is all about. Having or not having this notice means nothing in regards to how two pieces of equipment will interact. Anything imported into the US legally should have the notice and meet certain standards. That’s not to say some cheap “illegal” imported stuff or something that is defective might be in the mix.

    This could be coming from ANYTHING in the vicinity that runs on batteries or plugs into the wall. Usually the closer you are to the source the more if a problem it will be. Your body can act as a shield so when you move around relative to the source you may be shielding the noise at least partially.

    You could check each thing in the house. Start in the room you are in. Often turning off electronics doesn’t completely shut a thing off altogether. You need to pull the plug from the wall or remove the batteries. Everything and I mean EVERYTHING that runs on electricity is suspect, and you may have noise from multiple sources.

    Disconnect the power from one thing at a time and note the effect. This is a systematic process of elimination.
    I can just about guarantee that you won’t think of every possible piece of equipment that runs on electricity. Did you shut off the power to your pilotless water heater? Eh? See?

    Good luck with your quest.
    hrodbert696 and ctmullins like this.
  4. A shorter cable could help too, but...no not really. You're picking up other electronics. It kinda just is. When you play, it'll go away. Most people just turn off the volume between songs. Or, hit the mute switch. Or, use a noise gate.
  5. Gremson


    Mar 22, 2012
    North-Leftern USA
    Alright. So I'm back!
    From what I've read it really is "just is" for single coil pickups. It's pretty bad at some gigs and non existent at others.
    I've read that it's not an issue for humbuckers, so that makes me question my wiring. I wired my bass like a typical jazz bass setup. A volume for each pickup with a single tone knob. Doesn't this wiring essentially make the pickups humbucking? I wonder if I have the polarity backwards on one pickup. But I'm not sure if it makes a difference to which pickup, or how (if it's even possible) to switch the polarity. Any ideas?
    It's an old cheap Japanese bass, and I know I should expect some funky quirks. But I'd like to eliminate as many inconveniences as I can since it's the only instrument I have.
  6. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009

    if they're single coils then the pickups themselves have to be opposite coil winding and opposite magnet polarity from each other in order to hum-cancel together.

    your funky '70s japanese bass probably isn't that, so they hum.
  7. Gremson


    Mar 22, 2012
    North-Leftern USA
    Bummer. I was afraid of that. Thanks for the reply.
  8. It easy to find out quickly, if you have a compass.

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