Grounding/hum issue

Discussion in 'Pickups & Electronics [BG]' started by Lester87, Jan 18, 2013.


  1. Lester87

    Lester87

    Joined:
    Jan 18, 2013
    Location:
    The Netherlands
    I have a true bypass looper (in - out and send -return) which causes quite a bit of hum, I've opened it up and I believe it's not grounded properly. How can best ground it? Or could something else be causeing the hum?
  2. uOpt

    uOpt Supporting Member

    Joined:
    Jul 21, 2008
    Location:
    Boston, MA, USA
    The metal case, if any should be grounded. If the case is not metal you should have shielding foil or similar.

    If the hum persists you need to check what it on the other side of the cables connecting it. If the devices there are all connected to A/C power you might not have a shielding issue but a ground loop with potential difference. In that case you cut ground from one of the cables at this box.
  3. Lester87

    Lester87

    Joined:
    Jan 18, 2013
    Location:
    The Netherlands
    Yes it is a metal case, how/from where do I ground it?
  4. Bobster

    Bobster

    Joined:
    Mar 27, 2006
    Location:
    Austin, TX
    Hi Lester,

    Just a few questions....

    1. Does it hum when your hands are on, or off the strings, or just all the time?

    2. Any loose wires?

    3. If you have a multimeter, do you have a ground from the bridge to the pots and control plate?

    Thanks
  5. Lester87

    Lester87

    Joined:
    Jan 18, 2013
    Location:
    The Netherlands
    No the bass is fine, it's just the loop pedal that's causing the problem. I've tried my pedal chain with and without the looper and it's only causing hum when the looper is in the pedal chain.
  6. uOpt

    uOpt Supporting Member

    Joined:
    Jul 21, 2008
    Location:
    Boston, MA, USA
    Normally it would be grounded via the plug on the cable to the amp.

    However, that might not happen for a number of reasons. You should check with an ohmmeter.
  7. SGD Lutherie

    SGD Lutherie Supporting Member

    Joined:
    Aug 21, 2008
    Location:
    Bloomfield, NJ
    Disclosures:
    Owner, SGD Music Products
    Do you have it plugged into two amps? Or are any of the effects AC powered?

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