Ground Loops - Eliminating System Hum and Buzz

Clint DeBoer

Clint DeBoer

Banned
You’ve just connected your system and there’s a buzz or hum that won’t go away. You’re running your gear through power conditioners and you’re beating your head against the wall trying to figure out what’s up. Congratulations - you've just entered The Ground Loop Zone...Several weeks ago I was pulling my hair out after I installed a new component into Reference System 3 for review. It was an amplifier that came with a three-prong power cable. Immediately after placing the amp in my system a very noticeable 60Hz hum starting pouring from my speakers.

If this has happened to you the chances are it’s a ground loop between your Cable TV and another component in your system (like an amplifier or powered subwoofer). Now, how do you solve it? Check out this article for a surprisingly helpful way to combat this common problem.

[Read About Combatting Ground Loops]
 
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threewheel42

Audioholic Intern
if you have your house done in conduit, you or your electrician can possibly fix through setting up the appropriate wall outlet as an isolated ground. This is more of a long term fix to the problem.
 
Az B

Az B

Audioholic
threewheel42 said:
if you have your house done in conduit, you or your electrician can possibly fix through setting up the appropriate wall outlet as an isolated ground. This is more of a long term fix to the problem.
How is an isolator/transformer a temporary solution?

As the article states, the ground loop is most often caused by the cable ground, and the isolator fixes it. For a lot less money than calling an electrician in and setting up all your A/V outlets as isolated.

Ideally, it should be a free fix as the cable company should provide the isolator. But my cable company is particularly uncooperative and inconvenient, so it's far easier to order the isolator and be done with it.
 
I

Iffy

Audiophyte
Sattelite Ground Loop?

I've been able to narrow down my group loop hum to the DirecTV Tivo box. When unplugged the ground loop goes away. Could the connections to the sattelite dishes be causing it the way the cable connection typically does?
 
Clint DeBoer

Clint DeBoer

Banned
You can get an isolator for the audio connections from the DirecTV/Tivo as well.
 
Duffinator

Duffinator

Audioholic Field Marshall
Iffy said:
I've been able to narrow down my group loop hum to the DirecTV Tivo box. When unplugged the ground loop goes away. Could the connections to the sattelite dishes be causing it the way the cable connection typically does?
I'm having a similar problem with my RCA DirecTV/TiVo box. But it's also putting interference into my phone line as well. Is there a isolator that can be used on phone lines? I also have DSL on my phone line.
 
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Indiana Jones

Audiophyte
Dimmer related ?

I have had the same problem as with your reference 3 system (hum started after I added a 3 prong multi channel power amp to my system) except for the last point...removing the sat cable from the wall (or outboard tuner) did not remove the hum. Without the power amp in the system, the hum goes away as I am using a receiver. Since my theater lighting is controlled by a remote wall dimmer, could this be the cause of the hum...even though my amp and pre-processor go thru their own dedicated outlet ?

p.s. when I ran a ground wire on the chassis screws from my DVD, to the amp to the pre/pro (as recommended by a corporate Rotel technician)the hum level lowered quite a bit but it is still audible.
 
jaxvon

jaxvon

Audioholic Ninja
I'm not sure about recommendations, but yes it can definitely be dimmer related. I have a friend with a nice amateur studio and when he runs a PA system without a power conditioner, there is a really loud buzzing that comes from the speakers. He also happens to have halogen lighting on a dimmer switch. As soon as the lights are off, the buzzing will go away. You should maybe try running your system on a separate circuit from the breaker (if that's possible) as well as using the above suggestions.
 
I

Iffy

Audiophyte
Video "hum"

hawke said:
You can get an isolator for the audio connections from the DirecTV/Tivo as well.
Actually, I should have been more specific. My ground loop is manifested as a slowly scrolling line(s) in the video signal, rather than an audio hum. I'm going to see if it goes away when I keep the Tivo box plugged in, but detach the two satellite connections.
 
RLA

RLA

Audioholic Chief
Yikes
You need to add these common problems to the article
#1 If you have a heavy power cord or an outlet in the wall that is worn out
and wont grip the Hot/Neutral/Ground prongs on the plug the ground can make intermittent or light contact with the tang on the inside of the outlet
this will cause a Hum through the system I have seen this many times
best solution for this is to replace the out let with an industrial version
available at Home Depot for about $4 the only benefit is that the industrial version has better gripping and will hold the power cable better for all of you that have power line conditioners for large amps you know what I mean
If you are installing a front projection system ceiling mount this outlet is a must.
#2 check the polarity of the outlet it may be wired backwards you can get a polarity checker at Home Depot for about $5 This is the first thing I do
on a consultation with clients many times the Hot and the Neutral are reversed
on the outlet

#3 Light dimmers and other appliances that share the same circuit with the
outlet you have your gear on can cause hum's and Dimmers that share a common ground are a big problem as are florescent light fixtures

There are other problems that can cause hums that are associated with the internal parts of the amplifier they are for the most part easy fixes
depending on your skill level you may choose to look at them you do so at you own risk A dislodged or loose power supply will cause hum in an amplifier it may be as simple as tightning a screw or re epoxying the transformer to the chassis mount. A ground point in the amplifiers chassis that is loose can cause
low level hum. A worn out, loose or miss adjusted RCA input terminal can cause low level hum There are more but these are the most common
Hope this helps
Ray
 
C

ceningolmo

Enthusiast
I apologize, as this may be a profoundly stupid question. But, I need some clarification, so I will ask.

A quick list of what is hooked up... I don't know if anyone will need specifics to help me, but better safe than sorry.
Kenwood VR-8070-S Receiver
Sony DSP-NS775V DVD player
Dish Network 811 HDTV Receiver
D-Link DSM320 wireless media server

I do not currently have a power conditioner. I have a surge suppressor, but I don't believe it does any of the isolating or filtering that more expensive units do.

I have a buzz in my home theatre system. I recently purchased the Kenwood receiver, and the buzz started when I introduced it to the system. So, my first inclination is that the receiver is the culprit. My problem is determining how to fix it.

According to articles I have read, on this site in particular, ground loop hum is a common problem. When the ground loop problem is described it is generally referenced as an immediate problem that remains constant while the system is powered up. Perhaps I am wrong in this perception?

Is there a difference between a hum or buzz associated with ground loop problems and the buzz associated with some sort of line interference? I know that I should route my power, audio/video interconnects, and speaker interconnects seperately in order to prevent interference. Is this a different problem than the ground loop issue? If so, how does one deal with it?

My system never had a hum prior to the introduction of my new receiver. Also, the hum does not start immediately upon power up. Typically it is about 20-30 minutes in to music, movies, or TV before the hum becomes present. Does this indicate a different type of problem?

Sorry if this is all covered in an article somewhere. If it is, I just haven't found it. I would appreciate any help you can provide.

Thanks,

Ross
 
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techno_riker

Audiophyte
Satellite Grounding Problem?

I'm having a video hum problem. (Probably audio hum as well, though the video hum is unmistakable.)

I have a new Panansonic HTIB (http://reviews.cnet.com/Panasonic_SC-HT920/4505-6740_7-30895706.html) that I just hooked up to my system, which includes TV, VCR, and DirecTV satellite receiver. The HTIB main unit (DVD player) is connected to a powered subwoofer (active subwoofer). The video hum is only present when watching DVD's, not when watching the satellite.

The satelitte box has a 3-prong power cable, while the powered subwoofer has a 2-prong power cable. (The TV and VCR also have 2-prong power cables; the DVD player is powered by the subwoofer.) What I've found is that unplugging the satellite box eliminates the video hum.

I've tried plugging the satellite box into another power recepticle, including in another room, but the hum is still present in varying degrees. (I should mention at this point that my house is 80 years old, for what it's worth.) As a test, and using an extension cord with a ground recepticle, I plugged the satellite power cord ground (third) prong ONLY into the extension cord's ground recepticle, leaving the other two prongs unplugged. The hum came back. This leads me to believe that it is indeed a ground loop issue.

After reading many articles and posting on the site about eliminating ground loops and interference, I decided to try using an isolation transformer. I purchased this one:



...since I figured the Jensen was a bit expensive and I didn't even know if that would solve my problem. It did not solve my problem. I'm not even sure if it helped at all as I didn't see any noticeable reduction in hum. I tried connecting it at the wall outlet for the satellite cable, at the satellite receiver, at the point where the satellite receiver connects with the VCR... pretty much everywhere I could. No luck. Then I read somewhere--maybe on the Jensen site--that satellite receivers may not be affected by an isolation transformer. I'm certainly not sure.

Any guidance would be much appreciated. I'm guessing that something is not grounded properly but I really have no idea how to fix it.
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
techno_riker said:
I'm having a video hum problem. (Probably audio hum as well, though the video hum is unmistakable.)

I have a new Panansonic HTIB (http://reviews.cnet.com/Panasonic_SC-HT920/4505-6740_7-30895706.html) that I just hooked up to my system, which includes TV, VCR, and DirecTV satellite receiver. The HTIB main unit (DVD player) is connected to a powered subwoofer (active subwoofer). The video hum is only present when watching DVD's, not when watching the satellite.

The satelitte box has a 3-prong power cable, while the powered subwoofer has a 2-prong power cable. (The TV and VCR also have 2-prong power cables; the DVD player is powered by the subwoofer.) What I've found is that unplugging the satellite box eliminates the video hum.

I've tried plugging the satellite box into another power recepticle, including in another room, but the hum is still present in varying degrees. (I should mention at this point that my house is 80 years old, for what it's worth.) As a test, and using an extension cord with a ground recepticle, I plugged the satellite power cord ground (third) prong ONLY into the extension cord's ground recepticle, leaving the other two prongs unplugged. The hum came back. This leads me to believe that it is indeed a ground loop issue.

After reading many articles and posting on the site about eliminating ground loops and interference, I decided to try using an isolation transformer. I purchased this one:



...since I figured the Jensen was a bit expensive and I didn't even know if that would solve my problem. It did not solve my problem. I'm not even sure if it helped at all as I didn't see any noticeable reduction in hum. I tried connecting it at the wall outlet for the satellite cable, at the satellite receiver, at the point where the satellite receiver connects with the VCR... pretty much everywhere I could. No luck. Then I read somewhere--maybe on the Jensen site--that satellite receivers may not be affected by an isolation transformer. I'm certainly not sure.

Any guidance would be much appreciated. I'm guessing that something is not grounded properly but I really have no idea how to fix it.
Sorry to hear about your continuing problem. Does the hum go away when you disconnect the satellite feed altogether, not just turning it off?

Maybe your problem is elsewhere? It is a pain to isolate the cause but that is what must be done, finding the specific cause.
 
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techno_riker

Audiophyte
Success... or at least a measure of it

I thought some more about grounding, that maybe the recepticle is not grounded--it is an old house afterall. I have a protected power strip that I have all the power cords plugged into, and this power strip has indicator lights for "protected" and "grounded". While the "protected" light is always on, the "grounded" light is never on.

So I tried a test. I plugged the power strip into a much newer recepticle that was installed a few years ago (in a different room). The grounded light came on. Therefore, that seemed to indicate that the recepticle I'm using for the A/V components is not grounded. So I used an extension cord to connect the power strip (and thus all the A/V components) to the newer, grounded recepticle. Voila! The hum was reduced significantly, although there was still a very light hum present. I then unplugged the satellite power from the grounded power feed and plugged it into the older, ungrounded recepticle. The hum was eliminated completely. Cool.

BUT... Now I have to figure out how to ground the recepticle that is used for the A/V components. Oh joy. :(
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
techno_riker said:
I thought some more about grounding, that maybe the recepticle is not grounded--it is an old house afterall. .... The hum was eliminated completely. Cool.

BUT... Now I have to figure out how to ground the recepticle that is used for the A/V components. Oh joy. :(

Well, there are some solutions. Depending on your skills for doing it yourself, it may be inexpensive or expensive if you don't have any.
You can run a ground wire to the panel if it has been upgraded and grounded.
You could try an outside grounding rod if the wall recepticals are near enough to the outside. Run an extension cord from a grounded outlet. Or, run a leg from the closest outlet to the hi fi. Or, a new run from the panel to the hi fi.

At least you have the source of the problem.
 
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techno_riker

Audiophyte
mtrycrafts said:
You can run a ground wire to the panel if it has been upgraded and grounded.
I am going to try running a ground wire from the recepticle, down through the wall into the basement, and connect it to a cold water pipe if I can't find the house ground from the new panel. However, the recepticle work box is very old and I CANNOT punch out any of the plugs. It's maddening! :(

Got any suggestions? I think my next step is to try to drill a hole into one of the punch-out plugs, drive a screw in there, and then pull on the screw to bend back the plug and expose a hole. I already tried to drill a hole without success, but that may be because I don't have a drill bit for metal.

But first I am going to attach a ground wire to the recepticle and try grounding it first to see if I can make it grounded. No sense in going to all that trouble if I can't ground the thing.
 
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thud333

Audiophyte
Duffinator said:
I'm having a similar problem with my RCA DirecTV/TiVo box. But it's also putting interference into my phone line as well. Is there a isolator that can be used on phone lines? I also have DSL on my phone line.
You need to put a dsl filter on your phone line. It probably does not have anything to do with the ground loop from your tivo.
 
Bob R

Bob R

Enthusiast
"Suggestion #4:
Hum may also be caused by faulty earth grounds in your home’s electrical system. In the past, cold water pipes were often used for the earth ground, so it is important to make sure that your ground connection is still valid and has not become loose or corroded. The cold water pipe method may no longer be valid in some locations due to requirements that the water meter be isolated from the water mains with a length of PVC pipe, thus interrupting the ground circuit. The safest, and most reliable, approach may be to provide your own ground. This can be accomplished by having a licensed electrician drive at least five feet of copper-jacketed steel grounding rod into the earth, and using that for your grounding connection."

I've personaly driven that 5 foot stake in for a swimming pool ground, and it was worth the effort.

As far as the water line, mine is a hose, from the house to the street. I paid to dig that one up, twice.

Drive a spike and be happy. :D
 

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