any ideas on fixing a humming subwoofer amp

Discussion in 'Archived Threads 2001-2004' started by Andrew W, Feb 20, 2003.

  1. Andrew W

    Andrew W Supporting Actor

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    I have a cheap sub and until I can afford to replace it with an SVS box, it will have to do. It is an "always on" model and it has an slight hum. Can I replace any components such as caps or transistors to attempt to alleviate this noise?

    BTW: all components are plugged into a single Monster A/V power strip/filter which then plugs into the wall. I don't have cable or satellite TV either.

    Good quality cables all around.

    Thanks,
    Andy
     
  2. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Subwoofer hum is usually due to a ground loop. In other words, its usually due to some other condition rather than a fault of the sub itself - some of the best subwoofers will still have this issue. The ground loop usually comes into play if you have cable television. The ground reference for the cable signal is at a slightly different potential than your local ground.

    The quick fix is to use a "cheater plug" on the subwoofer's power cable. This converts the subwoofer's 3-prong power cable to a 2-prong plug that goes into the wall socket. But using this means that you no longer have a hard connection to the local ground signal and you'll have to decide for yourself if you can live with that long-term or if you want a safer connection. You can always try the cheater plug and if that works then you know its a ground loop problem and you can address this by isolating your cable input. Do a seach for "ground loop" and you'll get more info.
     
  3. PaulDF

    PaulDF Second Unit

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    OK, what if my sub has no ground terminal to begin with? I guess its obviously not a ground loop problem... My auto on is always on, and a hum is always there. It did it from brand new and is a replacement already, so not sure what to do. This sub is rarely in use, but I would kinda like to get it working properly! [​IMG]

    Any other ideas?

    P.S. Sorry to leach off your thread Andrew! But we seem to have similar problems.
     
  4. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Paul,
    Sorry, I don't know the answer to that one. Its possible that some bad component is leaking 60Hz noise through.
     
  5. Aaron_Smith

    Aaron_Smith Stunt Coordinator

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    Try moving the sub close to the receiver and using shorter interconnects. It is easy to pick up noise when a low-level signal is being sent a long way.
    Nice to see another Austinite on the board!
     
  6. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Yes, that's good advice. Also if you're using multiple segments of interconnect try replacing that with a single interconnect that's long enough to get to your sub.
     
  7. Aaron_Smith

    Aaron_Smith Stunt Coordinator

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    Also may help to run the interconnects in stereo, using both L and R inputs (if you're not already doing it).
     
  8. Rob Formica

    Rob Formica Stunt Coordinator

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    I don't know if this could be your case, but i've had a similar problem where my line-level wires were passing too close to the power cord and caused humming (RF noise?) in my sub. Simply rearanging the wires did the trick for me. [​IMG]

    later
    Rob
     

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