Subwoofer hum from in wall cable ...

Discussion in 'Accessories, Cables, and Remotes' started by JayPo, Mar 23, 2004.

  1. JayPo

    JayPo Stunt Coordinator

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    Sorry if this is the wrong forum, but the issue stems from my recent home theater construction.

    I ran a sub cable from my gear - through the wall - to a box behind my seating area. The cable was premanufactured low grade Monster. It runs perpendicular to a couple of power runs so I didn't think that it would be a problem. Like an idiot, I didn't test it. Now the wall is drywalled up and I can't seem to get it to budge when I pull on it, so no using it as a fish. Do I have any options left or should I just consider it useless now???

    Plugged in, it doesn't hum until I connect the rca cable. Help please, thanks.
     
  2. chris_everett

    chris_everett Second Unit

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    Well, make sure that the cable is the problem before giving up on it. Try getting an extention cord and plugging the subwoofer into the same power outlet-surge suppressor as the reciever to see if it's a ground loop problem. If you still have a hum, you can also try using a short RCA cable to temporarily attach the sub with, and make sure it's not a problem with the reciever.
     
  3. JayPo

    JayPo Stunt Coordinator

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    Hey Chris,

    Thanks for the response, I'll give the extension cord a try. But I didn't mention (sorry) that when the RCA is plugged into the sub - it hums ... EVEN WHEN IT'S NOT PLUGGED INTO THE AVR ON THE OTHER END ... again, sorry, that was probably an important piece of information. It actually sounds a little quieter AFTER I plug it into the AVR. Man, I'm hosed aren't I?
     
  4. chris_everett

    chris_everett Second Unit

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    Well then, that's it, it's the cable. You could try replacing the connector on the sub end, but your probably out of luck.
     
  5. JayPo

    JayPo Stunt Coordinator

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    Does anybody know if I slap down a Ferrite Choke Core ( Ratshack Choke ) if it will help any?

    Thanks.
     
  6. Rick_Brown

    Rick_Brown Second Unit

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    Ferrite choke is a cheap try, but also try plugging the sub's power cable into another outlet via an extension cord.
     
  7. JayPo

    JayPo Stunt Coordinator

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    Thanks guys. I'll let y'all know what the results are ...
     
  8. Wayne A. Pflughaupt

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    Jay,

    I’d try another cable before giving up on it. Run a temporary test cable across the floor and see what you get. If you don’t get the hum, you’ll know for sure it’s the cable in the wall.

    It’s likely the reason the old cable won’t budge is because the RCA jack won’t go through the hole in the wall box. If you cut the RCAs off you should then be able to use the cable to pull in a new one.

    Since you’re near electrical lines I suggest using RG-6. It will have an excellent shield. You can terminate it with twist-on F connectors, and then F to RCA adapters from there.

    Regards,
    Wayne A. Pflughaupt
     
  9. JayPo

    JayPo Stunt Coordinator

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    Thanks Wayne,

    I was just thinking of that exact same solution ... can get the adapters at PartsExpress or Ratshack and I already have a spool of RG6. Was just gonna cut off the ends, like you said and pull out the old wire, but since my ceiling isn't done yet, I was gonna run the new wire along that route.

    Thanks again,
    I'll keep you updated.
     
  10. Jon_Lon

    Jon_Lon Auditioning

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    I had the exact same problem except my cable run was quad shielded RG6 with the aforementioned adapters. Figured it couldn't be a ground loop with the cable disconnected at my amp but I tried a cheater plug on the sub anyway and it cleared it up. Might be worth a try.

    good luck.
     
  11. JayPo

    JayPo Stunt Coordinator

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    Jon,

    Just want to clarify, what do you mean exactly by a "cheater plug"? With ground to without?
     
  12. Jon_Lon

    Jon_Lon Auditioning

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    Without a ground. Not the greatest solution but it works.
     
  13. JayPo

    JayPo Stunt Coordinator

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    Ok, just to finish out this thread for anybody that is interested. The Choke didn't work, the plug didn't work, and it still hummed when I ran an extension cord back to the same outlet that it is normally in ... so I replaced it. Cut off the end of the sub cable, pulled it through. Fished a coax cable up the wall to the ceiling and back to my component room (instead of through the wall where the sub cable was). Bought two F to RCA (or F to Phono as RatShack calls it: F Adapter) adapters and replaced my RCA wall module with an F module (F Coupler) snap-in. Ran a coax patch from the plate to the sub and BOOM! NO MORE HUM!! ... but plenty of bumpin.

    Thanks for everybody's response
     

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