BFD owners need help with hum from sub and amp!

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

  1. Steve Morgan

    Steve Morgan Second Unit

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    Well, after a couple of months I finally got my cables together to connect my BFD and move both subs to the corner,A Paradigm Servo 15 and a Von Schweikert S/3.After connecting the BFD between the Ref 30 and the subs I noticed a loud hum coming from the VSA sub none from the Servo.I started to trouble shoot switching cables(brand new Cat cables from BFD to subs)Monster cables from the Y from the Ref 30 to the BFD.I put cheater plugs on the BFD and the Sub still could not get rid of the hum.After 30 minutes I deceided to take the BFD out of the path and guess what? No hum.I had the BFD plugged in to a Vansevers Model 85 line conditioner and noticed a hum coming from the 85 which it has never hummed. My equipment is on a dedicated line (20 amp).Any ideas from the BFD gurus? I'm stumped.I used the mono adapter plugs so I'm lost.I'd love to EQ my subs after spending a couple of hundred bucks on cable.

    Thanks,

    Steve M.
     
  2. Bob McElfresh

    Bob McElfresh Producer

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    Even with a power conditioner, you can get a ground loop. (Remember that you have 2 amps in your system, each with a electrical ground. The amp's job is to take very small voltage differences and amplify them. A slight difference in the electrical ground reference can cause a humm).

    Does the BFD have a 3-prong electrical plug? If so, try using a "cheater" plug that does not connect the ground. If not that, use a cheater plug on the amp that is humming.
     
  3. Steve Morgan

    Steve Morgan Second Unit

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    Bob, I have cheater plugs on the amp and also on the sub.This is whats baffling me.
     
  4. Bob McElfresh

    Bob McElfresh Producer

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    Try this: remove the cheater plugs from your subs. Does the humm go away?

    My guess is that the short interconnect you have going between the LFE port and the BFD is of the "broken-shield" variety (or the BFD does not continue the shield connection)

    To solve subwoofer humm, some interconnects have the shield of the coax connected to the RCA plug on one side.

    With both your subs having "cheater" plugs, it looks to the shield/outer part of the RCA connector for the ground reference. Putting in the BFD has broken that reference. So try putting back in the electrical ground by removing the cheater plugs.
     

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