BFD=hum from sub and line conditioner. Whats up?

Discussion in 'Archived Threads 2001-2004' started by Steve Morgan, Feb 23, 2002.

  1. Steve Morgan

    Steve Morgan Second Unit

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    After several months I had some time and finally got all my cables to move both subs to the corner and connect a BFD.

    The subs are a Paradigm Servo 15a and a Von Schweikert S/3.I am using Cat sub cables.The BFD is connected between the Ref 30 and the subs.I am using Monster audio cable from a Y from the sub out to channel 1 and 2 on the BFD. The BFD is plugged in to a Vansevers Model 85 line conditioner with a cheater plug.When I was adjusting levels on the the BFD I heard a loud hum from the VS sub the Servo was fine so I started to trouble shoot.I changed the cables and inspected them, put a cheater plug on the VS sub, switched cables from the Servo to the VS still a hum.After an hour I took the BFD out of the path and connected the subs to the Y from the Ref 30. Guess what? No hum!BFD gurus what could be the problem? After spending a couple hundred on the cables and the BFD I would like to EQ the subs. Anybody possibly have an answer to this problem?

    Thanks,

    Steve M.
     
  2. Jeffrey Noel

    Jeffrey Noel Screenwriter

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    You probably just need a cheater plug, which converts the 3 pronged plug of the BFD to a 2 pronger. Worked great for my BFD, no more hum!!!
     
  3. Selden Ball

    Selden Ball Second Unit

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    Are your sub and BFD plugged into the same wall outlet as the rest of your A/V equipment?

    Unfortunately, using a cheater plug can be hazardous to your health. Equipment with a separate ground pin grounds the case for your safety, so that internal shorts won't expose you to 110VAC, which can be lethal. Consumer equipment with 2 prong plugs is designed to isolate the case from the internal electronics. 3 prong equipment is not designed that way.

    One common cause of hum is plugging your A/V equipment into different power outlets. With different amounts of current flowing in the long power lines running back to your power distribution panel, they wind up with different ground potentials at the socket. This voltage difference causes current to flow in the interconnect cabling between your A/V components. This current is heard as hum and is seen as dark bars slowly going up the TV screen.

    Solution: use a power strip with enough outlets. A 15 Amp circuit can deliver about 1.5 KiloWatts. Most A/V configurations only draw a couple of hundred watts most of the time -- the equivalent of a few lightbulbs.

    Another major source of hum is the CATV cable coming into your house. It's supposed to be well grounded where it enters your home, but that ground point often is not the same as is used for your 110VAC power. Unplug it from your cable box to see if that helps.

    Solution: get a cable "ground isolator". They're readily available. Sometimes antenna baluns connected back-to-back will work, but it depends on their design.

    I hope this helps a little.
     
  4. Steve Morgan

    Steve Morgan Second Unit

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    Thanks for the help everybody.Problem solved.It was those F!@#$%g Monster cables from the pre/pro to the BFD.

    Seldon,

    All my equipment is on a dedicated 20amp line except the subs.Both subs are plugged into the same outlet. I still get a small hum from the SErvo but you have to put your ear to the speaker to hear it.When I turned off the ceiling fan even that little hum went away.

    Thanks,

    Steve M.
     

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