Ground Loops - Eliminating System Hum and Buzz

[Porcupine]

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.

[Davidbley]

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.

[agabriel]

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

[kleinwl]

"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.

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.

[check]

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]

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?

[phokus]

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!

[Methodical]

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]

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!  Our friends at Impact Acoustics detail how to resolve a ground loop to help you achieve noise free connection of your equipment.

[Read the Article]

[rick451]

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????