Sub hum with BFD off or on

**Dagoods** · **10-14-08, 08:15 PM**

Hello,

I need to ask for some help with my BFD please. I have the BFD 1124P and with it on or off I get a very loud hum through my Subs. I have run Rew and balanced all my speakers and I have the midi cable connected to the BFD. Gone through the setup on the BFD using the guide I found on this site. Thought I was ready download the filters onto the BFD and give it a test. I powered up one of the subs and got a loud hum. Got the hum no matter which one I powered up.

My configuration (not sure what other information you may need on the rest of the HT).

I tried the "cheater plug" on the BFD power and it made no difference in the hum. Tried different cables, both new ones with the 1/4 on one end and RCA on the other and an adapter plug (1/4 to RCA) with RCA cables and it made no difference.

I have tried to read through all the threads but know I must be missing something that is probally simple. If I need to go back and read something else please suggest it and I will.

2 Outlaw LFM EX's - front of the room
1 Hsu MBM - near field

I may not have provided enough information so please ask any questions you want. I am to the point where I am out of ideas and could really use some help.

Thanks for any and all help!

David

**weverb** · **10-14-08, 08:40 PM**

On the back of the unit, there are two push-in style buttons, are they in the +4db or -10dB configuration?

**Dagoods** · **10-14-08, 08:43 PM**

They are pushed in for the -10db configuration.

**weverb** · **10-14-08, 08:46 PM**

Do you also hear a hum coming from the 1124P itself?

**Dagoods** · **10-14-08, 08:58 PM**

I only hear the hum when I turn on one of the amps for a sub. With the sub amps off I don't hear any hum. The hum is low on one EX, loud on the second EX and very loud on the MBM.

**weverb** · **10-14-08, 09:01 PM**

Where did you get the 1124P from? Used? New?

**Dagoods** · **10-14-08, 09:09 PM**

New (sealed box) at Guitar center yesterday

**weverb** · **10-14-08, 09:13 PM**

Try exchanging it for a different one. It has been mentioned that there are bad units out there. Sorry I could not be more of a help. I think we covered all the basics I know of.

**Dagoods** · **10-14-08, 09:21 PM**

Weverb,

Thanks for all your help and suggestions! I will take it and swap it out with them tomorrow. They had three of them and one has to work. I will post tomorrow night once I have had a chance to hook it up.

I can't wait to see what improvements it will make.

Thanks again I really appreciate all your help!

David

**Wayne A. Pflughaupt** · **10-14-08, 09:46 PM**

I'm not seeing a reason to exchange it. weverb asked if the BFD itself was humming (as you'd be able to hear if you put your ear close to it), and you answered that the subs were humming. The fact that the noise stops when the amps are turned off confirms that the noise (and thus the problem) is a typical ground loop, not any fault with the BFD.

Regards,
Wayne

**brucek** · **10-14-08, 10:23 PM**

Quote:

I will take it and swap it out with them tomorrow

Why would you do that when the hum is still there with the unit turned off......

Disconnect all the subs and start simple with one sub and a BFD with no input. If no hum then connect a single input to the BFD. Have everything plugged into the same receptacle and see if it hums.

brucek

**Dagoods** · **10-14-08, 10:26 PM**

Wayne,

Thanks for the tip. I went and read some of the information on ground loops and from what I can determie I need to try a different cable that has the shield not connected on one end. I have disconnected the FIOS connection to see if the cable was the problem and it did not help.

Can you suggest any other areas I should check?

Thanks again,
David

**Dagoods** · **10-14-08, 10:28 PM**

Thanks for the tip. I will give it a try.

**weverb** · **10-15-08, 12:11 AM**

Quote:

Dagoods wrote:

I have the BFD 1124P and with it on or off I get a very loud hum through my Subs.

Whoops! Missed the part about the hum still present when off.

**Dagoods** · **10-15-08, 08:57 AM**

No problem it's all good! I appreciate all the help I can get with this. I am going to work on it tonight and see what I can find. I know I am close and just have to solve this last problem.

Thanks again to all who have offered help.

David

**Dagoods** · **10-15-08, 07:41 PM**

Guys,

I have solved the hum! I made up 2 cables today so I connected everything back up and I was in the process of disconnecting different pieces of equipment and checking for the hum and got to the DVR. I disconnected the coax and checked it again. The hum was gone. So I connected the coax back up and the hum was still gone. It should have come back but it didn't. I had pulled the coax out and routed it another way and had pulled it from a bundle of cables. Well in the process I moved the sub cables. So when I went to tuck away the sub cables the hum came back.

It turned out to be a bad y cable. It makes sense to me now. When I heard the hum it was louder on one of the EX's and the MBM. It was not very noticable on the other EX. The EX and MBM had the bad y cable.

So I am about to take a few measurements and load up my first house curve. I can't wait to hear it!

Thanks to all of you for your help and suggestions

David

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