[lovingdvd]

Thanks again Wayne. To answer your question, yes the electrical box is flush mounted to a wall.

I spoke to a friend who said that the electrical feed into the house carries a common ground, and that is what the electrical panel is likely grounded to. After seeing the neighbor's "pipe" set up the same as mine, I started thinking that perhaps the issue was not with the pipe not going into the ground.

So then I started thinking more about your messages about corrosion and Rich's recent success. As I looked closely at the catv ground wire, the lead was fairly corroded. Likewise the copper pipe itself had a layer of grim on it where the leads were clamped to it.

I took some general purpose sand paper and sanded down the leads and the pipe where the clamp connected everything. I removed the cheater plug, put my custom XLR isolation cable back in place, fired it up, and volia - no more hum!! So I believe this solves the issue - thanks so much.

One question though - if indeed things are properly grounded, should it still be necessary to use the custom XLR to isolate (lift) the ground like it does? The obvious answer is YES because I still have the hum without my custom connector - but just wondering if that is supposed to be the case.

Happy Thanksgiving everyone!

 

[Wayne A. Pflughaupt]

You should have no hum using regular XLR wiring (i.e. signal [-] to pin 1). So it looks like you’ve improved but not eliminated the ground loop.

Can’t say that I’ve ever heard of electrical service carrying a “common ground,” but then I’m not an electrician...

Regards,
Wayne

 

[lovingdvd]

UPDATE: Some interesting developments since we last left off...

I had my electrician come out. He checked all the internal wiring and said things were grounded properly. As it turns out there is a ground wire that runs from the electric panel into the foundation of the house. The copper rod on the outside is just a conduit of sorts to tie the phone and cable tv to ground.

He decided to check my outside meter box before leaving, and its a good thing he did. Open opening the box we discovered that there was a small, mist-like smoke coming from area where the two main electrical wires from the ground feed into the meter box!

There was also a brown-like reside on the inside of the panel, likely the residue from that smoke building up over time.

He wiggled something a bit and sparks shot out for a second like a sparkler! The power company came out that day to service the unit.

It turns out that one of the fiberglass-like insulator blocks had cracked and one of the leads was being slightly shorted to ground. They since repaired it and said that settlement of the house sometimes causes this and they have seen it plenty of times before. My house is about 7 years old. Its hard to know how long it had that wiring issue...

I'm not sure if this at all could have been impacting my ground loop. I'm going to try removing the custom XLR cable to see if the hum is still there since this wiring issue is now cleared up. I suspect the hum will still be present, in which case I'll just stick to the XLR (since it is perfectly silent with the custom XLR since I sanded down the copper pipe to improve the cable ground).

At any rate I am very glad to have caught that issue as it seems like a real hazard the way it was. A special THANK YOU to all of you helping here and making the point that something was amiss somewhere. Although this may not have been the source of that issue, it was the catalyst in discovering this problem and resolving it!!

 

[Guest]

So here's my twist/question on this whole situation:

Just had Directv installed with a dual tuner box. Got the hum; if I disconnect both cables going into the satellite box, the hum disappears, so I assume it's a ground loop issue. Looking outside yesterday, I don't see a separate ground wire running from the satellite dish to my cable panel in the outside wall of my house.

So, I'm assuming this should have been grounded? Additionally, the four cables running down from the satellite feed a 4x8 multiswitch, with cables that then run from the switch into my house. I don't see any grounding blocks anywhere - are all four cables running from the satellite to the multiswitch supposed to run through grounding blocks?

Tried all of the quick fixes found in the forums to eliminate the hum. The only thing that worked was to run a 14 guage copper wire from a screw on my directv receiver to a screw on the BFD. This eliminated about 75% of the hum, but I can still hear it. Would a thicker guage wire eliminate a greater portion of the hum, or am I off base with that?

Any help would be appreciated. Thanks.

 

[brucek]

are all four cables running from the satellite to the multiswitch supposed to run through grounding blocks?

Yes, I certainly run my cables through an outside grounding block before entering the home...........

I don't see a separate ground wire running from the satellite dish to my cable panel in the outside wall of my house.

I think it's smart to do this, but I don't know if every installation complies.

Would a thicker guage wire eliminate a greater portion of the hum

No, ground loops are very low current. It's not a power issue at all. It only requires a small potential difference on the grounds to cause a hum. Eliminating it simply takes a lot of trial and error.

brucek

 

[Guest]

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]

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

 

[Guest]

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]

should I just use two 2 in 1 blocks?

Just use two double blocks.....

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.

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]

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.

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

 

[Guest]

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

 

[allredp]

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! :help:

 

[brucek]

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]

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]

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]

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

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

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?

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.

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?

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]

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]

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]

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.

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]

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