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gounding amps in old house?

Discussion in 'Amps and Cabs [BG]' started by lumptoner, Feb 14, 2004.

  1. I have ground hum noise, in my old victorian house in san fran.,
    the ampeg and swr amps I use are fine at gig's, but hum like passive pickups, with either passive or active pickup bass's. the ground switch on the amps, does not eliminate it. the hum is directional, in that, turning to just the right spot, not always the same, reduces it. computers, radios, etc, do not have the hum. the wall plugs are three prong, but as the wiring is old it is only making a ground to the plug, or to a cold water pipe. I have use a headphone amp, on battaries, when the nosie, drives me to distraction. no hum, with the headphone amp. any idea's, besides moving. thanks-lumptoner
  2. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    You can test your outlets with a little ten dollar gadget you can get at any Home Depot or Radio Shack. Just plug the gadget into the outlet, and read the lights. If your house wiring is not correctly grounded, there's not a thing you can do in terms of fixing the hum problem (or, let's say, any effort along those lines will be wasted). On the other hand, if the gadget says your house wiring is "correct", then there are other things you can look at.
  3. bassmantele


    Jul 22, 2003
    Boston MA USA

    Could you clarify? Turning the amp to the right spot, or turning the bass?

    First, check the house wiring as mentioned above. If the room is wired properly, then...

    Does it happen with no cable in the amp input jack? If so, then it's internal to the amp, and not coming in from the pickups or cable.

    Are there any fluorescent lights or dimmer light switches nearby? Computers? TVs?

    Try turning off everything in the house. If you have circuit breakers open then all. If it goes away with everything off, then start turning things on until you find the offender.

    If nothing inside the house/apartment is causing the problem, then it must be coming in from outside. Is there another apartment in the house? Appliances in another apartment can cause problems.

    Any power lines nearby? If the offender is not in your house and there are no obvious sources nearby there could be a fault in the wiring outside the house.

    Take-home message: divide and conquor - house wiring, electrical devices, outside sources.
  4. QTraXQ

    QTraXQ Guest

    Aug 16, 2002
    San Antonio, TX
    A good test is to Unplug all devices like pedals and other sound devices from the amp.. If you turn on only ONE AMP(Head) with nothing attached do you get any noise???

    If you connect you Effects that you may use to the send/return do you get any noise??? Are any of the effects using an AC adaptor or Plug or battery only??

    Do you get any Noise as soon as you plug any instrument in with volume off and all pickups rolled off?

    You may need to use a "ground lift" on any extra device connected to the amp, but I would leave the amp Grounded...

    You could also have feedback bouncing back on the outlet from other devices around the house.

    I recommend anyone check Out This

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