Ground Loops - Eliminating System Hum and Buzz

P

Porcupine

Audioholic Intern
How can I fix my hum problem?

I have a decent idea of what is causing my hum problem but am not sure of a way to fix it.

My electrical devices: A computer which has all my music on it, with a 3-prong plug. The monitor also has a 3-prong plug. *All my other equipments only have 2-prong plugs.* My receiver, computer, and monitor are plugged into the same power strip. There is no hum on my receiver.

I have a SECOND receiver plugged into a different power socket. This is part of a different setup, for the TV. It is located about 12-feet from my computer. Again, all equipment besides the computer have 2-prong plugs. There is no hum on this system.

I ran line-level cables from my first receiver to my second, because I may want to play my computer's songs from a different location, through different speakers. Or I may want to play songs through many speakers at once (fake surround sound haha). However there is terrible hum on this system due to a ground loop problem originating from my 3-pronged computer. So I can't hook up both my receivers to my computer. :(

This problem goes away if I simply plug my second receiver into the same power strip as my computer, I have tried it. Furthermore my TV, DVD player, and other devices can all be plugged anywhere and no hum will result. Only the computer source is having hum problems. Unfortunately due to my setup (TV and computer on opposite sides of room) the power cords are not long enough to all plug into the same power strip (I only managed to do so for testing purposes, not when I have my equipment where I want them to be at). What can I do?

First of all I am confused because there is only one 3-pronged device in this entire setup...the computer. Don't there need to be two 3-pronged devices to cause a ground loop hum?

The easiest solution seems to be to get a power extension cable. I did, and thus extended my second receiver's power cord and plugged it into the same power strip as my computer. Unfortunately this power extension cable had 3-prongs on it and the hum did not go away. Would this work if I got a 2-pronged extension cable? Also I am worried because all the receiver manuals say "DON'T USE AN EXTENSION CORD WITH THIS PRODUCT"...why is that? Is it dangerous for me to do so? Thanks in advance for any help I might get.
 
D

Davidbley

Audiophyte
I spent a lot of time with my direct TV system trying to eliminate the 60 Hz hum in the audio. As it turns out it was NOT a ground loop problem, but a consequence of the receiver itself. Some Hughes satellite TV systems have a (I'm guessing here without access to schematics which Hughes will not release) a defective filter in the AC power supply and rectifier which allows 60 Hz noise to filter through to the audio circuits. If you need help email me and I can tell you what I know.
 
A

agabriel

Junior Audioholic
I understand that this thread is about how to eliminate ground loops however would it not be better to say that for the future perhaps fiber is a better medium for everything? I don't want to deal with ground loops - ever and I don't think others should either. I run fiber from the two components (DVD & cable box) that can give it. Granted my system is a bit simple probably compared to others but it seems that fiber A/V is better. Perhaps I'm missing something.

Anthony
 
K

kleinwl

Audioholic
Bob R said:
"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
NEC 2005 recommends 3 10' copper 1/2" rods (min 8' in ground) for a typical house (300Amps) ground. Seperation should be 8' between spikes. Running a complete circle is nice, but unnessary.
 
C

check

Audiophyte
I just added an older model Onkyo reciever/amplifier to my fairly basic system (Digital CATV, VCR and stereo TV) and subsequently encounter the buzzing problem from the amp speakers. I read the article on ground loops and tried, unsuccessfully, to isolate the source of the problem.

Through the TV audio setting, I turned the TV speakers off with either fixed or variable output and that did it. Unfortunately I don't have a remote for the amp/reciever and can't control the volume remotely. The Digital CATV remote was unable to program it. Are my couch potato days over?

Also, a symptom I discovered was that a similar buzzing (same frequency) is coming from inside the TV.

Do I need a new TV or is there a fix to isolate the TV speakers from the amp?
 
phokus

phokus

Audiophyte
Problem found, awaiting solution

I introduced a Jolida 502b stereo tube amp into my HT system to power the mains with a Harmon Kardon 525 receiver handling the processing and surround channels. Since they are both grounded plugs going into the same outlet, a seriously deafening hum was created. I plugged both into a Monster power condtioner and it took the deafening out of the hum, but it was still very noticeable. Since the hum wasn't there on the tube amp's other direct inputs, I knew it was the amp/receiver connection causing the problem. I picked up the Radio Shack Ground Loop Isolator RCA cable and that killed the hum almost entirely. Unfortuantely, it cuts the signal level so much that I have to crank the tube amp's volume to match the surround output levels and now the tube amp creates a hum from being pushed. It's also kind of dangerous since If i accidentally switch inputs on the Jolida without bringing the volume way down, it's going to blow my speakers out. Some would say any tube amp is going to hum somewhat, but on the other inputs like CD, the signal level is so much higher that you just can't put the volume level at 75% like it is on the receiver input without doing some structure damage to the walls - this is a powerful 60 watts!

Soooo is there a solution out there that doesn't require:
1 - running an extension cable from either amp to a separate circuit
2 - having an electirican rewire and reground the circuit
3 - using a cheater plug

Most ground loop problem solutions I've found are for the cable tv problem which I don't have. How do people with multiple grounded amps usually solve this problem? Would upgrading the Jolida's power cable help?
 
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phokus

phokus

Audiophyte
Update: I swapped the Jolida's stock, cheapo power cable with the sturdier one that came with the HK and voila, 95% of the buzz disappeared. The HK doesn't seem to be as affected by the power cable so it'll get the cheap one for now. I can't believe it was the power cable!
 
M

Methodical

Audioholic
System hum after connecting A500s & using Xtension cord

I got the infamous buzzing/hum in my system after connecting 2 Behringer A500s. So I figured they had to be the culprit. I began reading the Audioholics tips section on this subject and it hit me. In a rush to connect the amps to my system, I used an extension cord to temporarily plug in one of the amps and after reading the article it dawned on me. I unplugged the amp from the extension cord and the buzzing was all gone. So if anyone is using an extension cord this could be the problem.

Clint I don't recall if this (extension cords usage) is part of the ground loop article but maybe you'd like to add to it by stating "Do not use Extension Cords" or have folds check sources connected via extension cords when experiencing buzzing in the system.
 
gene

gene

Audioholics Master Chief
Administrator
<P><FONT face="Arial, Helvetica, sans-serif" size=2><A href="http://www.audioholics.com/techtips/audioprinciples/interconnects/GroundLoopPrimer.php"><IMG style="WIDTH: 125px; HEIGHT: 125px" alt=[comp2] hspace=10 src="http://www.audioholics.com/news/thumbs/comp2_th.jpg" align=left border=0></A>There is a humming sound coming from the speakers. A faint dark bar rolls from the bottom of the image to the top, changing colors and distorting the picture as it goes. What’s this? How is this possible? All this equipment is new and your home is only a few years old. Welcome to the nefarious neighborhood of the ground loop!&nbsp;&nbsp;Our friends at <A href="http://banners.audioholics.com/phpAdsNew/adclick.php?bannerid=376&amp;zoneid=32&amp;source=&amp;dest=http://www.impactacoustics.com/index_flash.asp?engine=ahjune"><STRONG>Impact Acoustics</STRONG></A>&nbsp;detail how to resolve a ground loop to help you achieve noise free connection of your equipment.</FONT></P>
<P><FONT face=Arial size=2>[Read the Article]</FONT></P>
 
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R

rick451

Audiophyte
ground loop ???

just up graded speakers to bmw L-R-C 600 series got hum in center channel
not caused by cable un hooked from system and wall when i watch a dvd no hum none on tape or phono or anything but when watching movie on cable.
also when i unpluged the reciver from wall and took to shop it was pluged in to similar system and no hum? not done yet!! brought back home and plug in worked great till 2 days later hum was back. i un plug and let stand till i used it wor s great. want it to work all the time. any ideas????
 
B

billhe2

Audiophyte
subwoofer hums

as the article says, I got 60hz hum out of my woofer using cable. I could eliminate it with a 3 to 2 prong electrical power plug adapter, but didn't feel comfortable letting the ground reference float. so I bought a transformer for my input cable (cable tv) which eliminated the problem.

then i switched to satellite and the hum returned. I removed the cable (which was now on my satellite input cable run from the dish) and the hum disappeared again. not sure why, but am not complaining
 
Clint DeBoer

Clint DeBoer

Banned
Just a head's up on an alternate item that costs a lot less. It will work to eliminate ground loops due to cableTV, but if you want the flattest response the Jensen may do better (plus you know they accurately measure and plot theirs):

http://www.cencom94.com/gpage.html8.html
 
J

jpontius

Audiophyte
Can't quite figure this out...

I have a Sony stereo receiver with 4 3-way speakers that I built, and a mackie 1200watt pro-audio amp powering an 18" sub cabinet, and I have been getting a selective buzz, but I can't seem to make sense of it.

-With the CD source, there is no buzz (even with the TV on), so I can conclude that it is not a problem with the CD player, receiver, or speakers, amp or sub together.

-With either video source (x-box or dvd player), the buzz occurs with all components connected. But if I unplug the video cable from the tv OR disconnect the Mackie, the buzzing stops. (however, unplugging the coaxial cable from the TV does NOT stop the buzzing)

Basically any signal that comes from a source that is also sending video signal to my tv has a buzz. I think this is strange because this is not an AV receiver... it's just a stereo receiver. Why would the video connection effect the sound if it is completely separate?

I have tried plugging the Mackie and TV into different outlets, and separating them by a large distance, but neither of these worked.

I am definitely no expert, but this makes no sense to me. Could you please help? TIA!
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
I have a Sony stereo receiver with 4 3-way speakers that I built, and a mackie 1200watt pro-audio amp powering an 18" sub cabinet, and I have been getting a selective buzz, but I can't seem to make sense of it.

-With the CD source, there is no buzz (even with the TV on), so I can conclude that it is not a problem with the CD player, receiver, or speakers, amp or sub together.

-With either video source (x-box or dvd player), the buzz occurs with all components connected. But if I unplug the video cable from the tv OR disconnect the Mackie, the buzzing stops. (however, unplugging the coaxial cable from the TV does NOT stop the buzzing)

Basically any signal that comes from a source that is also sending video signal to my tv has a buzz. I think this is strange because this is not an AV receiver... it's just a stereo receiver. Why would the video connection effect the sound if it is completely separate?

I have tried plugging the Mackie and TV into different outlets, and separating them by a large distance, but neither of these worked.

I am definitely no expert, but this makes no sense to me. Could you please help? TIA!

Since it goes away when you undo the cable TV, that is what causing it with its ground.

There are cable TV isolators for about $11:

http://www.cencom94.com/gpage.html8.html
 
J

jpontius

Audiophyte
I was under the impression that if unplugging the actual cable from the TV didn't stop the buzzing, the cable is not tha problem. Am I wrong about that, then? sorry... just making sure.
 
SWHouston

SWHouston

Enthusiast
Grounding – A Must !

I’m probably going to repeat several items/topics that have been said before, but it never hurts to be reminded. And, maybe you’ll read something here, that you hadn’t thought of.

The Electric Companies furnish a Ground to your Electrical Box:
BUNK, at best it’s poor! If you have your Lines run on Poles, all they do is run a Bare Ground (usually Aluminum) wire down the side of it, coil it around the buried end, nail it in place, and all you got to do is wait for a few years, and it will corrode away, and leave you “Groundless”, almost.
If you happen to have your Electric Supply buried, that’s even worse! Out of sight, out of mind!

Most newer houses, REQUIRE a Ground Rod. IF you don’t have one, get one put in! Besides the Safety issue, it WILL save you bunches of bucks over a few years in Electrical Cost. I could go into why that is, but, this Post is going to be too long anyway!
IF you have one already, DON’T trust it being solid. The connection to it, the wire, is usually pretty close to the earth, and needs “RE-Clamping”, every couple years. You CAN do this yourself, if you’re even a little handy with tools, no need to bring in an expensive Electrician for this. You need to take it loose, Wire Brush the Rod and maybe cut off a little of the wire, and tighten it back up tightly.

You can also look in your Electrical Distribution Panel, it won’t bite you if you’re careful! The Ground wires may be on a separate Block by themselves, but, if they’re not, that’s ok, and they will share the Neutral Buss, with the White Wires. This/these connections should be checked for tightness too. You can do this yourself.

You have a Ground Wire through out your house:
Maybe you do, and maybe not! Even if it’s there, frequently it’s not connected/contiguous, specially if they’ve used Plastic Receptacle Boxes. Sorry, but, you need to look in EACH one, and see that the group of (usually bare) wires, are twisted together and capped with a Wire Nut, and one wire from that twist, is coming up to the Ground Screw on the Receptacle.
WHAT!, your receptacles don’t have ground screws! Of course they don’t, that cost money in construction, and “MAYBE” they ran a little wire under where the receptacle tightens up to the Box.
RLA mentioned using a “Industrial” Receptacle in his Post #11. You may be better off asking for a “Hospital Grade” Receptacle, those have a little Green Dot on the Front of them.
Hubble Electric is a VERY reputable manufacturer, and stay away from P&S, they’re lousy! You pay exactly for what you get there, expect at least $4-6 for a good Grounded Receptacle, with strong gripping force. Hospital Electrical Requirements (in my locale), require 15oz pulling pressure, to remove the Plug.
You can test one right there in the Hardware Store, stick a Plug in it, and if it’s easy to pull out, that’s the wrong one to buy! Usually that Screw will be colored “Green”, but as long as it’s connected to the “Strap” that goes around the Receptacle, and tightens up to the box, that’s the one!

FYI: and don’t batch me out for this please !
ROUND Post in receptacle is the GROUND wire, has a Green Screw to connect it to, Green or Bare wires.
NARROW Flat Blade in Receptacle is the HOT, has a Gold/Brass colored screw to it to, Black/Colored wires.
WIDE Flat Blade in the Receptacle, is the NEUTRAL wire, has a Silver colored screw to connect it to White wires.

I mention this since I KNOW you’re going to go around and check all your receptacles, IF you find one of these Receptacles, that is not wired as above, that’s called “Reverse Polarity”, and IF you have a Buzzing or other problem with your Audio, and are using a Polarized Power Cord/Plug with the system, that just could be the reason. And if there is a Reversed Polarity somewhere in your house, that’s being used by a Grounded piece of equipment, that could very likely cause a interference problem. SO, are you more willing now, to check those things out ? Maybe !

But what if I miss verifying a connection/polarity somewhere, what do I do !
This situation is more likely than not, you can use a Electrical Polarity Checker” if you have one to do this, as RLA mentioned in his Post #11,or if you want to, get a long/50’ piece of spare wire, any gauge, clamp it on the nearest metal COLD water Pipe (like under the Sink), and use your Analog or Electronic VOM (Voltage Meter) in the Ohms Scale, to verify continuity. Just clip the Black Lead from your Meter to it (the long wire), and pull it around to all the Receptacles, to check them out. It’s a temporary Lead Wire.
Be sure to Zero the Meter with the Long Wire in circuit, where you’ll get a fairly accurate reading on “resistance”. It should be Zero Ohms, with an Analog Meter, and less than .001 with a good 4 Digit Electronic Meter. BE SUE to stick the Red Probe into the ROUND hole in the Receptacle when using the Ohms Scale, but, it’s a good time to see if you’re getting good Voltage to the Receptacle too. That would be the Narrow Blade, and remember to change the Meter to the ACV (Alternating Current-Voltage) Scale. Good voltage is more than you think. Should be 120/125 Volts, not 110 or less !

Ground you System every chance you get !
If your System comes through the Attic, find a GALVANIZED Pipe to ground to. Most of the Splitters for your TV Distribution System have (or should) a screw, to ground them. DON’T use a BLACK Pipe to ground to, that’s usually Natural Gas, and not a good idea. BUT, don’t ground to a HOT Water Pipe either.
Many of the newer Hot Water Heaters have a Fiberglass Tank, and if you ground to the Hot Pipe in the Attic, it may NOT be connected to Ground, as you would expect a Cold Water Pipe to be.
Many houses have PVC Piping in them, for both Hot and Cold, but, if you go to your Hot Water Heater, and see that it has Steel Galvanized Pipes supplying it, you can “Bridge” these pipes, and get good continuity.
Just get two Pipe Clamps and a short piece of (12 Gauge) wire, and electrically tie them together (sort of a jumper wire). Taking the Tank out of the Circuit.
IF you can’t tell Hot from Cold in the Attic, go to the nearest Bathroom(s), and run the Hot Water for a while. Then go feel of the Pipe, and clamp to the one which is not hot.

Other than that, you probably got it fixed, but, remember that all the Audio and Video Cabling you’re using behind your System, carries a Shield. That’s a common Ground to every piece. But, doesn’t hurt to run a separate small Ground Wire to the Components, specially if they have a Grounding Lug on them. Turntables are very prone to have Lugs/Ground Wires, which need to be grounded to your Amp.

You guys still spin some Vinyl, don’t ya ! :D

Have a good Day ! :)
 
D

Dolby CP-200

Banned
The easiest and fastest method I’ve stumble across is a screen piece of wire cable and just connect one end to an amplifier and over to the next amplifier, if the AVR or AP or the separate amplifiers have a fixing screw on the back just follow the above f you don’t have such a fixing screw on the back just use the side screw that hold the amplifier together.

9 times out of 10 I usually get lucky;) but there’s always the one that will elude you for hours on end.:confused:

Note: here in the UK we’re on a 50Hz 210v mains system.
 
SWHouston

SWHouston

Enthusiast
DCP,
Where there's a will, there's a way, good for you !

This may be a little off topic, but, in the UK, does your electrical supply have a Ground wire like in the US, or do I remember it just being two wires?

And, is there a collective 210v, like each wire is 105v to a Neutral or Ground source ?

Have a good Day ! :)
 
SWHouston

SWHouston

Enthusiast
Understood, It's a shame we (USA) didn't adopt a system like that, would save us a BUNCH of money. (Increase the Voltage/Decreases the Amps).

Have a good Day ! :)
 

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