What solution do folks use for the dreaded BFD hum?

**ckaye99** · **12-18-07, 04:26 PM**

Wow, thanks for the quick reply. Just realized I spelled gauge wrong, what a tool.

As for grounding the 4 coax cables running from the satellite:

Does anyone make a 4 in 1 grounding block, or should I just use two 2 in 1 blocks? Do I ground them before or after the multiswitch? And finally, can I connect a wire from the multiswitch to the house ground directly, in lieu of grounding each of the coax cables?

As for trial and error, phew, never done so much plugging/unplugging/switch outlets in my life. Such fun.

Thanks.

**Wayne A. Pflughaupt** · **12-18-07, 05:35 PM**

With my Direct TV, both RF feeds go through a grounding block which is located just below the antenna. There are wires going from the grounding block to the antenna and the main electrical ground stake. Since I didn’t get a ground loop, I assume this is the correct installation method.

I suggest making the installer come back out and do it right. If he give you any grief, complain to Direct TV.

Regards,
Wayne

**ckaye99** · **12-18-07, 06:40 PM**

You say "both RF feeds;" I have 4 coax cables coming out of the dish, not 2. I'm not sure how this compares.

And I thought I read somewhere that daisy-chaining the ground as you described it is actually not a good idea.

**brucek** · **12-18-07, 06:47 PM**

Quote:

should I just use two 2 in 1 blocks?

Just use two double blocks.....

Quote:

Do I ground them before or after the multiswitch?

Mount the blocks outside before the switch. It's nice to mount the switch indoors for troubleshooting when its poor weather outside.

I mounted my blocks outside and then ran the grounds (along with a dish ground) to a 8' rod in the ground nearby. Then that rod is bonded to the central house ground with heavy ground cable. That way, I have an outside path to ground before it ever enters the house.

Quote:

can I connect a wire from the multiswitch to the house ground directly, in lieu of grounding each of the coax cables?

Nope....

brucek

**Wayne A. Pflughaupt** · **12-18-07, 06:50 PM**

Quote:

You say "both RF feeds;" I have 4 coax cables coming out of the dish, not 2. I'm not sure how this compares.

Doesn’t matter how many you have - they should all be going through a ground block.

Quote:

And I thought I read somewhere that daisy-chaining the ground as you described it is actually not a good idea.

They aren't daisy-chained. If one wire from the ground block goes to the ground stake, and the other goes to the antenna, that's essentially a direct path from the antenna to the ground stake.

Besides, that has to do with the grounds on electrical circuits (not that I buy it), not this.

Regards,
Wayne

**ckaye99** · **12-19-07, 03:33 PM**

OK, I think I've got it guys. Thanks very much for the quick help on this matter. Have a nice holiday.

**allredp** · **12-21-07, 12:20 PM**

Great--I thought I dodged the dreaded hum problem!

Without too much backstory, I've been running the BFD for nearly a year between my Yammy rx-v1200 and my SVS pb12+/2. No hum, 4 filters, happy as can be.

Then I get a break financially and decide to upgrade to a Sherbourn 5 x 200 amp and the new Yammy rx-v1800 as the pre/switcher.

Now that I'm hooked up (with the BFD between the Yammy using an XLR to RCA 18" cable and an RCA to RCA with 1/4" adapter between the BFD and the SVS) I have a hum through all the speakers and I can very much hear the hum from the BFD itself, which is back inside the equipment closet. Haven't checked to hear a hum through the SVS or not.

So, I'm at odds over why I get some hum now and not with my previous setup?

I have the Sherbourn amp's 2 powercords going to their own 2 gang box on one side of my equipment closet, and I have the BFD, Yammy and other componenets going through a power-surge protector and connected to a seperate 2 gang box on the opposite side of the closet.

Help!

**brucek** · **12-21-07, 02:14 PM**

Quote:

I have the Sherbourn amp's 2 powercords going to their own 2 gang box on one side of my equipment closet, and I have the BFD, Yammy and other componenets going through a power-surge protector and connected to a seperate 2 gang box on the opposite side of the closet.

You just answered your own question...............

brucek

**allredp** · **12-21-07, 04:58 PM**

Hey BruceK,
Sorry to be so dense! Help me know how I answered my own question!!!
I actually called Sherbourn to see if they knew what was causing it--he said to just get a couple "cheater" plugs, which I did, and the hum is still there...
When I plug in and power up the BFD it has its own hum from the unit itself. When I take it out of the loop and just fire everything else up the speakers still hum--but the SVS doesn't.
Aarrgghh...
Thanks for any help!

**allredp** · **12-21-07, 05:19 PM**

OK, Brucek, I think I see what you mean.

I've gone back over this thread and I see where you said that using different recepticles for the amp and pre-amp may cause this problem.

So, I'll go try that out and let you know.

**brucek** · **12-21-07, 05:30 PM**

Quote:

Help me know how I answered my own question!!!

OK, sorry, I've been in such a rush lately...

Quote:

he said to just get a couple "cheater" plugs, which I did, and the hum is still there...

Can you tell me where you tried the cheater plugs and the results? Did you try one on the BFD itself, and what was the effect to the sub hum?

Quote:

When I plug in and power up the BFD it has its own hum from the unit itself

By this you mean a mechanical hum from the metal case itself, and not from any speakers? This is another issue and certainty not related to the addition of an external power amplifier.

Quote:

When I take it out of the loop and just fire everything else up the speakers still hum--but the SVS doesn't.

Are you saying that if you leave the BFD in the sub circuit, that it also hums in addition to the new hum you're getting from your main speakers?

Quote:

You just answered your own question

This comment was to indicate that the nature of any properly installed ganged box is that each of the two receptacles in the box will be powered from a seperate circuit. Each circuit will be on an opposite leg of the service panel. This is a recipe for a ground loop.
As a test, unlug your entire HT except for the power amp and receiver (being used as a preamp) plus the sub and BFD. Plug these things into a single receptacle and see if the hum is there. Granted there may not be enough power to run your whole system this way, but it's a test to see if powering from a common leg will remove the hum.

brucek

**allredp** · **12-23-07, 02:41 AM**

Man, I've tried so many different things to no avail...

Cheater plugs, isolating everything down to the amp and avr alone, checking to see if the CableOne guys grounded their stuff outside, etc.

I've definitely got something introduced by the amplifier or the avr. I guess my next thing is to just try the avr by itself to test that...

BTW, everytime I power down I get a sharp "snap" sound from my speakers (not very loud, but noticeable).

Do I have a faulty unit? Since I've not ever heard this noise in my setup before it stands to reason that one of the new pieces (the Sherbourn or the Yamaha) is the problem, right?

I really appreciate the help!

**imbeaujp** · **12-23-07, 06:59 AM**

Hello, I recently added a BFD between my Rotel processos RSP-1098 and my Rotel RB-1080 sub amp. All thoses equipments are on a Rotel RLC-1040 line conditioner. The interconects between the BFD and the amp are XLR - XLR, and RCA - 1/4 between the Processor and the BFD.

Before the insertion of the BFD in the audio line, there was absolutly NO noize, Nothing, Niet. I must admit that now, I got a little noize on the sub. I can ear what I call a 'processing' noize when I am verry close to the sub, but this not seem to be an 'electrical ground' noize.

My conclusion at this time is that the BFD is quite a nice product for features, but not a HI-FI product.

Maybe the velodyne SMS-1 has better results ?

**brucek** · **12-23-07, 12:18 PM**

Quote:

BTW, everytime I power down I get a sharp "snap" sound from my speakers (not very loud, but noticeable).

Not uncommon at all for power amplifiers. The manufacturer will usually attempt to design an elegant shutdown, but it all costs money. It's a bit easier for the receiver to do a proper silence shutdown since the processor and power amp is in the same chassis and can be sequenced.

Anyway, you've got the right idea, that you have to strip the system down to nothing and start to build it back up until you identify the culprit causing the loop.

Quote:

My conclusion at this time is that the BFD is quite a nice product for features, but not a HI-FI product.

It's completely fine for a sub though. Don't be fooled into thinking a ground loop has a particular specific 'sound'.
Most people use a BFD with zero hum, buzz etc. You have a ground loop and you'll need to find it if you want your buzz to go away....

brucek

**Wayne A. Pflughaupt** · **12-24-07, 07:04 PM**

Quote:

allredp wrote:

Man, I've tried so many different things to no avail...

Cheater plugs, isolating everything down to the amp and avr alone, checking to see if the CableOne guys grounded their stuff outside, etc.

Have you disconnected the cable line from the system to see if that’s the problem?

Regards,
Wayne

**Trekari** · **01-26-08, 11:19 PM**

Well, if I use cheater plugs on the BFD of my system as well as on my plasma TV, I get slight hum with my cable feed connected.

If I disconnect my cable feed from the wall outlet, without cheater plugs, I get no hum.

So clearly my problem lies within my cable feed. The moment I hook or even touch the coax to the wall outlet I get hum through all of my speakers.

**brucek** · **01-27-08, 07:30 AM**

Quote:

The moment I hook or even touch the coax to the wall outlet I get hum through all of my speakers.

You need to check if the cable is properly grounded to your house ground. This is usually done where the cable enters the home near the service panel.

**Trekari** · **01-27-08, 01:07 PM**

I already have Comcast coming out today between 4-6pm as this symptom is present on all my coax jacks

Up until I started getting serious about my home entertainment, I never understood what made my bedroom subwoofer make a crazy loud hum if I jiggled the cable the wrong way.

Now I believe that also is a 60hz hum being transmitted, as I have those devices also plugged into the coax (cable internet) in one way or another.

**Trekari** · **01-27-08, 11:20 PM**

A special thanks to brucek, wayne, and HClarkx for their help in my humming problems.

These links also proved to be useful in both understanding what a ground-loop actually is, as well as troubleshooting methods to resolve them.

http://www.audioholics.com/tweaks/co...m-hum-and-buzz

http://forum.ecoustics.com/bbs/messa...79/180767.html

http://www.epanorama.net/documents/g...e_solving.html

I ordered the Jensen transformer, and I'm hoping to put it where my CATV coax comes into my condo, before the splitter sends it to my 3 rooms. That would solve the problem at all ends, otherwise I will settle for getting my main entertainment system fixed.

-Jason

**Wayne A. Pflughaupt** · **01-28-08, 01:22 PM**

Since this is a perennial problem, I’m making this thread a sticky.

Regards,
Wayne

**Trekari** · **01-30-08, 04:48 PM**

So my Jensen transformer arrived today.

Basic rundown of the symptoms:

1) With cheater plugs not installed on my 3-prong devices, I had audible hum from subwoofers and satellites if the cable coax was connected to the TV.

2) With a cheater plug on the TV and Behringer, I still had slight hum when the coax cable was connected.

3) With cheater plugs and no cable coax, I had zero hum.

4) Without cheater plugs and the cable still disconnected, I had zero hum.

With my new MFW-15 subs, I still had a VERY slight hum if the Behringer was connected and the coax was also connected.

I installed my Jensen transformer as the first device after my coax feed enters my condo, before the splitter that connects my bedrooms/living room to the main feed.

I then went over and turned on all my audio devices, and only have an audible HISS at near-reference volume, which can easily be attributed to the noise-floor being amplified.

I HAVE NO HUM!

The Jensen Transformer worked like a pro for me.

**WmAx** · **01-31-08, 10:15 AM**

I do not know if this has already been posted in the thread(frankly, it's a long thread and I don't intend to read all of it), but Behringer has a new passive ground loop isolator. It also has balanced to unbalanced conversion. I have not had one to measure, so I can not comment on it's frequency response.

Behringer HD400

http://www.zzounds.com/item--BEHHD400

-Chris

**RyanH** · **07-10-08, 09:47 PM**

I just hooked up my BFD/amp setup with my new sub and got the hum. I have a Belkin PureAV power console where my cable TV connects as well. I had my BFD connected to a separate strip, but after reading some of this thread I tried plugging it in to the Belkin and the hum is gone. I don't know where my ground loop was, but this fixed it.

Advertisement