Ground Loops - Eliminating System Hum and Buzz

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Title Loans

Audiophyte
Thank you i was searching for better ways to eliminate hum on my end while i am djing. i know the macbook pros have grounded circuits which help and everything i have is grounded but i still find some hum no matter what in my microphone. i will try this routing method and see what happens.
 
F

FourTwo

Audiophyte
Thank you for posting this. I discovered a hum in my garage setup when I added a component last night. I will try this.
 
J

Jeffrey S. Albaugh

Audioholic
Video "hum"


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.
What you are experiencing is a Hum Bar that moves up thru the picture and repeats ad nuseum. Here is one easy way to eliminate it. You can run solid copper line to connect your electrical ground with your cable ground. Commonly, you could connect too the cablr=e ground if it is grounded to the copper on an outside water pipe. When you joint the two, it will go away. Good luck.
 
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Jeffrey S. Albaugh

Audioholic
"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

For my own HD Antenna on my roof, I ran thick copper line (insulated) down to the ground. I drove an 8' copper rod down 6' + into the ground which created an actual earth ground.
 
K

kenwstr

Audioholic Intern
I came across an article "Grounding and Shielding Audio Devices" on The Rane website, Google should find it. I am still reading through it but so far, very informative. Whatamess the industry has made!

Ken
 
B

bikdav

Full Audioholic
My desktop PC was buzzing bad. I stuck a ground loop isolator between it and the av receiver and that noise was GREATLY reduced.
 
C

cheyne

Audiophyte
Hey everyone, first time poster on audioholics. I also put my conundrum on the AVS forum as well to try to get as much advice as possible, so if you see my post on there then just ignore it. I'm just looking for a little help in determining how to correct a potential ground loop problem in my system.

My HT setup consists of a Marantz SR7009 AV receiver connected via the pre-outs to an Outlaw Audio Model 5000 power amp - these 2 components are running a 7.1.4 atmos setup using a 7.1 base-layer of Pioneer SP-PK52FS Andrew Jones speakers and 4 Atlantic Technology IC-6 OBA ceiling speakers for the atmos. My other relevant components are an LG OLED C6 display and an Oppo UDP-203 disc player, as well as a Samsung Time Warner digital cable box and a BIC F12 sub.
I do not believe my issue to be super complicated but since some of the symptoms are confusing (at least to me, lol) i thought i should reach out to the pros on this forum for some advice on how to proceed.
I did research and troubleshoot this on my own for about 2 weeks prior to posting on this thread so allow me to explain the issue: For my 2 rear atmos ceiling speakers i am getting a plainly audible hum from those 2 speakers only. I suspect the issue to be a voltage potential difference between my Marantz AV receiver and the Outlaw power amp but i need clarification on this.
I first discovered the humming issue when the only components i had connected to my AV receiver were the HDMI audio-only for my Oppo player and the HDMI coming from the cable box; the Marantz was connected to my LG C6 OLED tv via the main HDMI out from the Marantz. I use the 5 channels on the Outlaw amp to power the front L/R/C channels and my 2 rear ceiling speakers.
Initially i unplugged the co-ax cable cord and the HDMI cord from my Samsung digital cable box to see if that was the problem but the hum remained. Next, (and i left it this way) i tried plugging both the AVR and the Outlaw amp into the same power socket (the socket outlets were verified to have proper grounding) but there was no change. Since the AVR has a 2-prong power cord and the Outlaw amp is a 3-prong i plugged them both into a surge protector power strip but this also had no effect. The last thing that i tried was to connect the metal chassis of the Outlaw amp to the metal chassis of the Marantz AVR w/ a single cord of 16-gauge speaker wire, and this approach did finally cut the volume of the hum coming out of those 2 speakers by about 70%, however, there is still a slight hum present that is audible during quiet movie scenes. This is how i arrived at my suspicion of a possible voltage potential difference between the AVR and the amp. If that is the case then i'm assuming that properly grounding all the components to a single point will address that issue.
Now, here is the strange part: any time i watch a movie that has a Dolby Atmos soundtrack the hum essentially disappears and the atmos track works/sounds great, but if i watch a movie with any other kind of soundtrack - i.e. a DTS-X track, etc. - the slight hum reappears. Also, if i select the input on the Marantz AVR for my Samsung digital cable box (HDMI in - Sat/Cable) the hum once again essentially disappears and i get the normal upscaled atmos output "Surround" mode for my tv channels as i should and it works fine.
Any advice on how to better isolate/proceed with removing the remaining light humming noise is much appreciated!
 
Pogre

Pogre

Audioholic Spartan
I have a hum that's directly connected to my cable box. After some researching I found that this is a pretty common issues with cable/satellite set-top boxes. I don't watch DTV much any more so unplugging the HDMI to my satellite box isn't a big deal and it completely solved my hum.

Try unplugging the HDMI from your cable box when the hum appears and see if its stops. At least then you might be able isolate the problem.
 
S

sukhwinder

Enthusiast
Hi,
I got my Sr7012 marantz receiver and now i am hearing a static noise from the speakers. I think it a ground loop issue but i dont know. Becuase I bought a UPS backup Battery and connected the receiver to that even that has now helped. Now i have order a EBTECH HUMX- POWER LINE 60HZ GROUND HUM BUZZ FILTER hopefully this fixes. But if you think you know what it can you please tell me.
 
E

Ernie Schmuntz

Junior Audioholic
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]

I had the same issue after adding three pronged amp to system. I removed every connection from my receiver. I added the sub connection from the LFE to the new amp and powered receiver. No buzz? I started to add connections back one at a time. The snotty turned out to be the Comcast connection. The cable had a amplifier installed as a sleazy way of working around slow service. It puts AC on the cable. I do have a Monster power box. I ran the cable to monster, then to the DVR. Problem solved.
 
J

joshk03

Audioholic
I came across an article "Grounding and Shielding Audio Devices" on The Rane website, Google should find it. I am still reading through it but so far, very informative. Whatamess the industry has made!

Ken
Ah, sanity. The articles talks how chasis ground should only be connected to the enclosure, not the circuit board. I was shocked last year when I discovered this happens. My post here:
Power supply discussion on BLF
And then I was informed it is common :O
 
highfigh

highfigh

Audioholic Overlord
Thank you for posting this. I discovered a hum in my garage setup when I added a component last night. I will try this.
If your garage is detached from the house, does it have a sub-panel? If so, the feed should include a bonding conductor and GFCI outlets. Being on a concrete slab is dangerous when the electrical system has grounding issues. DO NOT use a ground lift adapter UNDER ANY CIRCUMSTANCES! Lift the ground when you're holding a mic or some other connection that's grounded and YOU become the load.

FYI- THOSE WEREN'T DESIGNED TO LIFT GROUNDS, THEY WERE DESIGNED TO GROUND EQUIPMENT THAT HAS A GROUNDING PIN WHEN THE OUTLETS DON'T HAVE A SEPARATE GROUND CONNECTION.
 
highfigh

highfigh

Audioholic Overlord
I had the same issue after adding three pronged amp to system. I removed every connection from my receiver. I added the sub connection from the LFE to the new amp and powered receiver. No buzz? I started to add connections back one at a time. The snotty turned out to be the Comcast connection. The cable had a amplifier installed as a sleazy way of working around slow service. It puts AC on the cable. I do have a Monster power box. I ran the cable to monster, then to the DVR. Problem solved.
Call Comcrap and have them do their job- it's their responsibility to ground the feed.
 
S

Speedskater

Senior Audioholic
My Authority Having Jurisdiction (AHJ) requires additional ground rods for new detached buildings.
Cable TV, telephone & internet lines often bring a ground problem with them.

That BLF thread covers a lot of ground, but in general for a hi-fi component that is not double-insulated:
a] the Safety Ground/Protective Earth needs to be connected to the chassis near where the AC cord enters the chassis.
b] the DC supply common needs to be connected to the chassis at a single point.
c] the audio circuit common needs to be connected to the chassis at the same single point as the DC supply common.
That point should be near the audio input connectors.
 
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joshk03

Audioholic
There is a fundamental difference in the way AC power is implemented vs DC.

AC completes it's circuit using the planet instead of a wire returning to the source. The AC neutral wire is actually just a rod in the ground at your nearest sub-station. And AC earth is just a backup rod in the ground near your house. AC earth was added in for safety because back in the day most things that plugged in happened to have steel enclosures. Without AC earth, and in the rare and dangerous case where a hot wire came loose and flopped against the metal enclosure (of a Milwaukee drill for example), the next person to touch it was electrocuted. But with AC earth connected to the drill case, the person was safe and the AC earth wire took the load until the breaker had time to trip and shut off the outlet. That's really it. AC Earth was mostly put there to keep your body is safe. It also provides RF protection, but that's not it's main purpose.

The confusion comes because DC circuits often call their negative wire a 'ground' wire. Calling it that should be stopped. Now sometimes the device needs RF shielding. RF shielding is supposed to be a Faraday cage design to create radio silence inside the box... With no connection from the the Faraday cage to the board because that would defeat the purpose. To do one better, there should be a wire from the cage into the soil outside like AC earth, but not shared with AC earth. Since requiring a new ground rod for DC's RF shielding is not desirable, designers can get dumb and just connect the cage to DC negative. Which ACTUALLY makes the DC negative float wildly in response to the cage... But that gives the appearance of it working because you eliminate the voltage difference between the cage and the DC negative.
 
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highfigh

highfigh

Audioholic Overlord
My Authority Having Jurisdiction (AHJ) requires additional ground rods for new detached buildings.
Cable TV, telephone & internet lines often bring a ground problem with them.

That BLF thread covers a lot of ground, but in general for a hi-fi component that is not double-insulated:
a] the Safety Ground/Protective Earth needs to be connected to the chassis near where the AC cord enters the chassis.
b] the DC supply common needs to be connected to the chassis at a single point.
c] the audio circuit common needs to be connected to the chassis at the same single point as the DC supply common.
That point should be near the audio input connectors.
Thanks for mentioning the ground rods- I forgot to do that.
 
S

Speedskater

Senior Audioholic
'josh' the DC part of your post is totally incorrect. Planet Earth works the same way with DC as with AC. In the past, we didn't see much high voltage DC in contact with Earth. But now some electric cars have high voltage batteries and in an accident, the safety worker have to be careful not to electrocuted.

* * * * * * * * *
Note: the DC part of the preceding post as been corrected.
 
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TLS Guy

TLS Guy

Audioholic Slumlord
'josh' the DC part of your post is totally incorrect. Planet Earth works the same way with DC as with AC. In the past, we didn't see much high voltage DC in contact with Earth. But now some electric cars have high voltage batteries and in an accident, the safety worker have to be careful not to electrocuted.
Yes, it is incorrect and VERY dangerous advice. I can tell you from personal experience from working on tube gear in years past that high voltage DC gives you one Hell of a jolt, when you touch the HT line in service.
 
J

joshk03

Audioholic
Speedskater & TLS Guy,
you guys were right about my post, I started off wrong on the DC paragraph. I was rushing, thinking low voltage experience, and made a mistake. I edited the post to correct my mistake now.

Speedskater, they work the same, but should never be connected together.
 
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