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Help - Subwoofer constant thumping

Discussion in 'Speakers & Subwoofers' started by Dave>h, Mar 6, 2019.

  1. Dave>h

    Dave>h Second Unit

    May 1, 2004
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    Recently purchased an older M&K sub for my home theater. Has worked flawless until recently when it has developed a thump, like a heart beat.

    IT comes and goes. I haven't done a lot of experimenting but I have the following facts:

    1) when I unplug the RCA connect to the sub, noise goes away.
    2) when I unplug the RCA connect tot he sub, the noise actually moved to the right surround speaker (only) and it only did this once. I couldn't replicate it.
    3) the noise isn't constant until it is constant. That is, I can start things up (projector, amplifier, xbox one) and there will be nothing and then it starts up after about half an hour maybe. I haven't experimented enough to get a actual time or how consistent that scenario is. Once it starts it is a constant thump thump thump like a heart beating.
    4) The noise was there whether I was watching netflix or gaming - thump thump thump...

    There is static on the volume knob of the subwoofer so I am thinking maybe it is related to that. Haven't added any new components or done anything different but I did get one heck of an electric shock when I touched the main speaker (not the sub) last night.

    Any insight or help greatly appreciated.

  2. Malcolm R

    Malcolm R Executive Producer

    Feb 8, 2002
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    Sounds like a grounding issue, given the humming and electrical shock. You should check your power connections and see if things are properly grounded. I'm not an electrician, so I'm not exactly sure what's involved. I think you can buy an inexpensive tester at hardware or home stores to check if your power outlets are wired/grounded correctly.

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