# not antoher hum!



## moreira85 (Jul 10, 2008)

Not anther post on the BFD hum! I read through the sticky and was just looking for some simple answers. I have the BFD dsp 1124 and just discovered a low sounding hum. It could have been there before but I just noticed it when I upgraded my receiver. I have an emotiva amp (3 prong plug), yamaha Rx 667 (2 prong plug), Dish network vip 722, and svs pb 12 plus 2 (2 prong). It took me a long time to find out what was causing this hum. I even unplugged the coax coming in from dish and still no change. When I remove the sub cable between the receiver and the BFD the hum stops or if I unplug the power from the BFD it stops. If i run the Sub cable from receiver straight to sub there is no hum. So currently I have removed the BFD until I can find a fix. I know from reading that I can build a cable but I was looking for a few other options?
I do not want to trick the bfd but making it a 2 prong because I dont want my kids to get electicuted!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Hi moreira,

It should be clear from reading through the BFD hum thread that no single remedy worked for every user, and indeed remedies that worked for some people didn’t work for others. So there’s no universal quick and easy answer. You’ll just have to work your way through the process, starting with the recommendations that are the cheapest and/or easiest.

Regards,
Wayne


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## moreira85 (Jul 10, 2008)

Thanks Wayne,
Is it safe to connect a ground to the screw on bfd frame to the ground terminal on the back of receiver? I have 2 young kids and don't want to shock them.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Sure that would be safe, but I don’t think that would make using a ground lift okay (if that’s what you’re asking). Maybe it will help with the noise. But since you only seen to have the problem when the BFD is connected (i.e. you’ve determined it has nothing to do with the satellite feed), I’d suggest making the cable that floats the signal ground connection at the BFD.

Regards,
Wayne


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## moreira85 (Jul 10, 2008)

Thanks you were right it really didn't help. Guess I may have to make the wire. I just want to be sure that making this cable will solve the issue. How do I confirm by trying a cheatter plug to confirm it goes away first?
Would this adapter work just as well as making the cable?
http://www.sweetwater.com/store/detail/Lifter/


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## Wayne A. Pflughaupt (Apr 13, 2006)

There’s no way to say for sure if making the cable will solve the problem. You’ll just have to try it and see. To be clear, you need two cables – one for the BFD input, one for the output. 

As far as the adapter goes, note that the description says “The Whirlwind Lifter... disconnects pin one to isolate the ground of a *balanced audio signal.*” If you AVR is like most, it only has unbalanced outputs. 

I just thought of one “quick and easy” solution you can try: An XLR cable between the BFD and the PB12. If that doesn’t help and you do end up needing to make the input cable, using the XLR cable between the BFD and PB12 would at least keep you from having to make the output cable.

Regards,
Wayne


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## moreira85 (Jul 10, 2008)

Makes sense Wayne but when I unplug the sub from wall I still get hum. If I unplug from receiver to bfd then it stops. So not sure if xlr from bfd from receiver will work.


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## ghost rider (Dec 29, 2010)

Wayne you’re going to blast me for this but I had nothing but trouble with my bfd a year ago and resorted to the dreaded cheater plug. Bryston actually told me to use a cheater plug on one of their older 3b that I have. The new ones come with a ground lift.

So is there something with the bfd that makes more dangerous than the Bryston products. My guess is in fact there is very little risk, although it’s not likely you can agree with that. 

So what could happen? Or more importantly what has happened as a result in using a cheater plug on a bfd.

I really like how the bfd coupled with REW flattened my subs out. I don't know if I can make it work with out it.


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## moreira85 (Jul 10, 2008)

I tried the cheater plug and hum is gone. I am not comfortable using one. Someone on another site told me to use the cheater plug with radioshack adapter transformers ie xlr/1/4" male and xlr 1/4 inch female adapters for input n output on bfd. They said by using the cheater w/ these adapters the receiver would ground the bfd.
Is this safe?


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## ghost rider (Dec 29, 2010)

I just tried running a XLR from BFD to my pre/pro. The BFD chassis is grounded and I don’t have any hum. I assume the ground from the XLR is providing a ground. So now in the event of a short it will take out my pre/pro.

I’m not actually that concerned. I’m the only one that will ever touch the unit. It would take a very unusual set of circumstances that I could ever touch the unit in a way that if it were shorting I would get anything more than a quick jolt. I have been shock by 20 amps dozens of time. Electrocutions with house hold currents that don’t involve standing barefoot in a bucket of water generally are a result from physically grabbing a device, cable, pipe and the muscles contract and you are unable to let go. It would always be a fingertip or the back of my hand as I would be reaching arount it and brushed up to it.

I guess Wayne is absolutely correct in how he advises members and after all it is your own risk but if I could figure out how to fix it correctly I would.


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## Wayne A. Pflughaupt (Apr 13, 2006)

moreira85 said:


> Someone on another site told me to use the cheater plug with radioshack adapter transformers ie xlr/1/4" male and xlr 1/4 inch female adapters for input n output on bfd. They said by using the cheater w/ these adapters the receiver would ground the bfd.
> Is this safe?


I really don’t see how that can accomplish anything, safety-wise. Take a look at this wiring diagram, which shows how one of those 1/4” – XLR transformers is wired. (Ignore the ground lift switch – there won’t be one with the in-line transformers you’re talking about. The ground line will be straight through.) 










As you can see, the sleeve of the 1/4” plug is common with Pin 1 of the XLR. Pin 1 in turn is common (has continuity) with the chassis of the BFD - and the safety ground lug of its power cord (IOW, the chassis of the BFD, the ground lug of the power cord, and Pin 1 all have continuity). 

So, lifting the BFD’s safety ground means that Pin 1 is also disconnected from ground. IOW, no safety ground is possible through the transformer, merely by its presence, if the power cord safety ground is lifted. Pin 1 does get continuity back to the chassis of the unbalanced source component (the AVR), though through the sleeve of the 1/4” plug (and subsequent RCA) . However, you could accomplish the same thing by simply running a wire between the chassis of the BFD and AVR. 

Regards,
Wayne


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