# Two final BFD questions...



## jschaefer7406 (Feb 5, 2009)

Hello again,

First off, thanks to all who have answered my previous questions about the 1124P. I do have two more questions though. First, I know there are a lot of threads about humming in these units. I have read a lot of them, but I am new to this world of balanced/unbalanced connections, cheater plugs, etc., so I thought I'd inquire about my specific situation. Here is what I have: being an old house, I have no ground wiring. I will run the BFD into a power strip that is plugged into a 3-prong wall outlet, just has no ground wire. For the signal, I have a single RCA-RCA cable (RS 42-2368) from the receiver, then an RCA splitter (RS 42-2535) into the BFD to run both channels. The channels are then run through adapters to a mono (unbalanced?) 1/4" plug (RS 274-320). Using the same part number adapters and RCA cables to then transmit to the sub amps. Am I guaranteed to have a humming problem, or should I try it and see? I don't have a huge budget for professional cables, hence why I used the Radio Shack units. Ideas?

Second question, should I leave this thing on at all times? I know others have reported popping in the subs when powered up. Will it harm the unit (or lose my presets) to leave it switched on and connect the power to my switched receiver output?

Thanks for any help,

Joe


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## Otto (May 18, 2006)

Hi Joe,

I think there are three separate potential sources of hum.

1) Some BFDs themselves actual have a buzz to them. That is, the unit itself has a hum. I've had two of these units, and neither hummed. This type of problem is caused directly by the BFD.

2) It's possible to pick up a hum in your system in the low-level signal cable. That is, the cable that connects between the receiver/preamp to the BFD, or the cables that connect from the BFD to the amp. These can be balanced or unbalanced signals. Balanced connections will effectively remove any effects of noise picked up along the path of the signal cables. If your receiver/preamp does not have balanced outputs, you will have to use unbalanced cabling (unless you get a "Clean Box", or similar, which will convert your unbalanced signal to a balanced signal). If you don't have balanced outputs on your receiver/preamp, I would suggest that you first try the unbalanced connections. If you are having problems with noise on the lines, you might consider the "Clean Box". It's more likely to pick up noise over long runs of low-level signals (low-level signals are generally those other than speaker connections. RCA cables (aka "single ended") and balanced connections are both low-level signals. Optical Toslink is not susceptible to noise, and digital coax is also rather unlikely to pick up noise, but for the worst cases. This type of problem is generally caused by system setup and isn't really the fault of the BFD. You could address hum in the signal lines by keeping those connections away from AC lines, and by maintaining the shortest low-level runs possible.

3. There could be hum from a ground loop in the system. This is usually addressed by removing the ground through use of a cheater plug. I think it's common in systems that have some cable box or another (can't remember which or what circumstances). This type of problem isn't necessarily the fault of the BFD, but it might be a contributor. More likely, it's probably a grouping of things in the system, up to an including the electric work of your home.

I believe that you should leave the BFD on all the time, and I do (using DCX2496 now). The BFD can and will create a LOUD pop when it's turned on (assuming your amp is already on; if you _always_ turn your amp on after the BFD, you'll be fine). I do not like the pop. While it never caused any damage, it just doesn't sound good for the system. It will not harm the unit to leave it on all the time in any way. On the other hand, if you did choose to turn it off, the presets will NOT be lost. At power on, it will return to the last setting it was on. IIRC, if you fully remove power to the BFD (i.e., pull the plug from the wall), it will power on to preset number 10 (I think).

Good luck!


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

Hi Joe,

Noise/ground loop problems are not a “given” when using the BFD. Most often the problem can be traced to a poorly grounded satellite dish or cable TV service. Since you don’t have grounded electrical service, even those problems might not be an issue for you.



> For the signal, I have a single RCA-RCA cable (RS 42-2368) from the receiver, then an RCA splitter (RS 42-2535) into the BFD to run both channels. The channels are then run through adapters to a mono (unbalanced?) 1/4" plug (RS 274-320). Using the same part number adapters and RCA cables to then transmit to the sub amps.


 It sounds like you’re running a single cable and splitting it into both channels of the BFD, then combining it back into a single cable out to your sub amps? I hope not – this is entirely unnecessary. Generally, you only need to use one channel of the BFD. The only reason to use both would be if you had more than one subwoofer at different locations in the room.

Also, Radio Shack has cables with an RCA on one end and 1 /4” on the other, so you don’t need to use those adapters.

http://www.radioshack.com/product/index.jsp?productId=2103850

Regards,
Wayne


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## jschaefer7406 (Feb 5, 2009)

Wayne A. Pflughaupt said:


> It sounds like you’re running a single cable and splitting it into both channels of the BFD, then combining it back into a single cable out to your sub amps?


Wayne,

I am spltting the signal before the BFD to feed both channels (obviously ). After the BFD, one channel is going to my front subwoofer pair (splits again before enterng the 2 channel amp). Other channel is feeding my rear subwoofer (again, splits to feed both channels). Make sense? I am planning to use both sets of filters independently, hence why I am running both engines. I would use the RS 1/4-RCA cable you mentioned, but I would need to split it anyway to feed both channels. If it's going to be split anyway, is it that much better than what I have? Do those 1/4-RCA adapters suck up that much signal? I purchased all parts based on the REW connection guide (which shows adapters). Please advise...

Thanks,

Joe


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## brucek (Apr 11, 2006)

> Do those 1/4-RCA adapters suck up that much signal?


They don't _suck up_ any signal. 

I've used them on my two systems for over ten years now and they're perfect.

brucek


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## jschaefer7406 (Feb 5, 2009)

Brucek,

So do you think my system wiring described above will work okay then?

Thanks,

Joe


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

> After the BFD, one channel is going to my front subwoofer pair (splits again before enterng the 2 channel amp). Other channel is feeding my rear subwoofer (again, splits to feed both channels). Make sense?


Thanks for clarifying, I wasn't clear on what you were doing from the BFD outputs to the subs.

Nevertheless, you still might be using more splitters etc. than you need. If you're using a two-channel pro audio amp for the front subwoofers, it probably has a "parallel" setting that will let you drive both channels from a single input cable. If your rear sub is a self-powered model, typically only one input is needed for those as well, not both (check the manual). But aside from being a waste of money and needless complication, it's not a huge deal to use the extra splitters and stuff.

Regards,
Wayne


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## jschaefer7406 (Feb 5, 2009)

Wayne,

Thanks a lot for all of the help. I know if I disconnect one of the two cables to the rear, the sub is substantially quieter. Therefore, it does seem to benefit by the use of a splitter. As for the front, I am running the Audiosource AMP-110, but I don't think it has a parallel mode. You got me thinkin though...

Thanks again,

Joe


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