Ideas to safely eliminate ground loop hum from 3 sources

Jim_814

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Jul 31, 2017
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This may be a somewhat lengthy question, and I apologize in advance, but I have been dealing with this problem for quite some time and would like to finally (safely) fix the problem. My current home theater consists of the following: Emotiva XPR-5, Emotiva XPR-2 and Emotiva XPA-5 amps, Marantz AV7702mkII preamp, LG OLED65E7P television, XBox 360, XBox One S, DirecTV 4K Genie Mini, Oppo UDP-203 4K UHD Player and Roku Ultra. The amps are on their own, dedicated 20-amp circuit and the rest of the equipment are plugged into an APC H15 Power Conditioner. For speakers, I have an SVS PB13-Ultra Subwoofer and Paradigm Prestige 95F for L and R, 55C Center, 25S x4 for sides and surrounds and CI Elite E80-A x4 for ceiling speakers for Dolby Atmos. All of the components are connected via Bluejeanscable Belden Series-FE Bonded Pair HDMI cables, all connections between the Marantz preamp and the amps are via BJC Belden 1800F Balanced Audio Cables with Neutrik XLR connectors and the speakers are all connected via BJC Belden Series 5000, 12 AWG cable with banana plugs.

My problem is that I have found 3 sources of ground loop hum and I am looking for the best and safest way to get rid of the hum. The first source is the Oppo Blu-ray player. Simply, when it is plugged in, I get the hum; when it is unplugged it is gone and when it is connected with a three-prong to two-prong adapter, the hum is gone. I was thinking that something like this (Ebtech Hum X Voltage Hum Filter) may get rid of the hum, however, I am open to other ideas.

The second source of ground loop hum is the coax cable for the DirecTV coming from the wall. When I look at the satellite dish, it looks like it has a proper ground wire from the splitter on the outside of the house, leading directly into the ground. Inside the house, the wire from the satellite dish is fed into a splitter and then distributed to the various rooms with DirecTV boxes. In my home theater, when the Genie Mini is plugged in and connected to the Marantz preamp (via HDMI), there is no hum. As soon as the coax is connected to the Genie, the hum appears. When the coax is disconnected, the hum disappears. I changed the coax cable from the wall to the Genie and the hum decreased by about 50%, however, it is still noticeable. I didn't know if this problem would be solved by doing some different kind of grounding of the wires/box or if something like this (Viewsonics VSIS-EU Cable TV Ground Loop Isolator) would be helpful.

The last (and worst) source of hum is my recently completed and connected computer. The computer is in a different room, plugged in to a Cyberpower CP1500PFCLCD UPS and connected to the Marantz via the same kind of BJC HDMI cable. The power supply in the computer is a Corsair AX1500i. There is an audible hum when the computer is connected, however, the hum increases to levels which make games unplayable when the graphics cards (two 1080 ti's in SLI) are being used past 50%-60% usage. At that point, the hum is louder than the game. I think this is a ground loop issue, because when I used the three-prong to two-prong adapter on the computer, the hum is completely eliminated (even at high GPU usage). Also, when I am playing games with desktop speakers plugged into the same outlet as the computer, there is no hum. I was wondering if the same hum filter (Ebtech Hum X Voltage Hum Filter) would help with eliminating this hum also. I read it has a 6-amp max. I'm not sure how much power my computer pulls. I also read that an online, double conversion UPS may eliminate the ground loop. Do you think either of these would safely work or do you think there are any alternatives.

Finally, I have read some about ground lifting and wondered if something like this (Hosa GLT-255 XLR Female to XLR Male Ground Lift Hum Stopper) connected to each of the 11 amplifier inputs and 1 to the subwoofer would help (and be safe) without loosing quality of sound. Thanks in advance for any help anyone could provide!
 
You are correct that you should only have one earth or ground for the house but connecting them to each other doesn't solve that. You would have to rewire all the grounds to one rod. There is often a difference between two grounding locations. There is a tool called a megger that is designed to find the best location for a ground rod.
http://www.electriciantalk.com/f2/ground-rod-resistance-16224/
 
The EBtech filter you link to should work for all the ground loops caused by AC. 6a continuous is a lot of current so I don't think that would be a problem. I have used ground lifters many times in the past and knowing that it's not good standard practice I can't remember an actual problem doing it.
A good electrician might be able to fix the AC grounding issues,
You could call DTV about the grounding issue on the satellite. The lead from the dish is not the same as standard cable or ova antenna so you might need a specific type of isolation.
I suggest these products for ground problems
http://www.jensen-transformers.com/home-theater/
I don't think you need to isolate the amp inputs.
You can find some info here on ground loops
http://web.mit.edu/~jhawk/tmp/p/EST016_Ground_Loops_handout.pdf
 

Jim_814

Prominent
Jul 31, 2017
2
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510
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Great, thank you for the suggestions. On my way to work tonight, I did look at the side of the house and noticed that there are two ground rods going into the earth. They are approximately 5-6 feet apart. They are both near where the electricity line enters the house and on the opposite side of the wall as the main breaker boxes. Both of the rods have a large black cable exiting the brick and connecting to the rod as it enters the earth. One of them has the cable internet and DirecTV dish directly attached to it. The other rod has only the large black cable. Should I connect these two rods with wire? I think I remember reading somewhere that if your house has more than one ground rod, they should be connected to make sure they are all at the same potential or something like that. I have the hum/ground loop eliminator plugs ordered from Amazon and I will try them. It would be nice if simply connecting these two ground rods eliminated all of the ground loop problems I am having. Thanks again!
 
You are correct that you should only have one earth or ground for the house but connecting them to each other doesn't solve that. You would have to rewire all the grounds to one rod. There is often a difference between two grounding locations. There is a tool called a megger that is designed to find the best location for a ground rod.
http://www.electriciantalk.com/f2/ground-rod-resistance-16224/
 
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