Ground Loop Hum AVR/Amp/HDMI

P

Pike44

Enthusiast
I have officially read more than I ever wanted to on ground loop hums but everything I keep finding is different than what I am running into. I have a Marantz 7013 (2 prong) that is hooked up to a D-Sonic 3 ch amp (3 prong) among other equipment. All equipment except projector is on the same outlet via WattBox surge protector. From checking power sources and inputs, I found I am getting the hum from when I have the HDMI cable (Binary B6A) from my projector or HDMI cable (standard Binary) from Control4 EA-3 Controller plugged to my AVR. I am going to give HumX possibly on the amp, but wanted to check if I am missing anything else that could be the issue here? To me the issue seems to be a combo of those 2 HDMI inputs and connecting the Marantz to the Amp but with power off having same issues is the ground loop the Amp and the HDMI just side effects? Can't quite wrap my head around it. Thanks for any feedback.

Everything powered off (at surge protector) except Amp:
Amp connected RCA(SVS SoundPath) to Marantz: Hum with either HDMI mentioned connected. No hum when both HDMI are disconnected from AVR

Everything powered on:
Same result. Hum if they are connected. No hum when both HDMI are disconnected.

Everything powered on but Amp RCA disconnected from Marantz (Amp to speakers only):
No hum even with the HDMI cables connected.

Not sure if this helps source the issue but I had to remove the 12v trigger from the Amp to the Marantz as it made the hum go through all 11 speakers versus just the front 3 the amp is connected to.
 
Last edited:
WaynePflughaupt

WaynePflughaupt

Audioholic Samurai
The only thing that jumps at me is the projector. Try plugging it into the same outlet as the rest of the equipment. The plug it’s using might be on the opposite phase from the other gear.

If that doesn’t work, I’d try ditching the surge protector and trying a straight power strip.

Other culprits for ground loops are cable TV service feeds and satellite feeds that are grounded somewhere besides the main house electrical earth ground stake.

Regards,
Wayne A. Pflughaupt
 
P

Pike44

Enthusiast
The only thing that jumps at me is the projector. Try plugging it into the same outlet as the rest of the equipment. The plug it’s using might be on the opposite phase from the other gear.

If that doesn’t work, I’d try ditching the surge protector and trying a straight power strip.

Other culprits for ground loops are cable TV service feeds and satellite feeds that are grounded somewhere besides the main house electrical earth ground stake.

Regards,
Wayne A. Pflughaupt
I will give that a try with an extension cord, but this is where I'm confused since with the projector unplugged from electrical as well as everything except the amp, I am still getting the hum with the HDMI connected to the Marantz. Also the Control4 unit doing thesame thing is powered the same location as the rest of the equipment and does the same thing even without power. I do not have any cable TV or sattelite connections. Just a shield, Blu-ray player, Control4 unit, amp, speaker outs and HDMI out to the projector.
 
P

Pike44

Enthusiast
I will give that a try with an extension cord, but this is where I'm confused since with the projector unplugged from electrical as well as everything except the amp, I am still getting the hum with the HDMI connected to the Marantz. Also the Control4 unit doing thesame thing is powered the same location as the rest of the equipment and does the same thing even without power. I do not have any cable TV or sattelite connections. Just a shield, Blu-ray player, Control4 unit, amp, speaker outs and HDMI out to the projector.
Just got done plugging the projector into the same outlet as the rest of the equipment with no difference made. The hum continued with the 2 HDMI's mentioned being plugged into the Marantz whether electrical was plugged in the attic or with the other equipment. When removing the HDMI connections from the Marantz the humming stopped again. At this point I am still leaning the issue is originating with either the Amp or the Marantz due to the amp connection as with the pre-outs removed, there is no issue even with those 2 HDMI inputs attached. I feel there has to be some connection to this and not being able to currently use a 12v trigger without the hum spreading from my amplified speakers to all 11 speakers. I won't get the HumX until Friday so unless someone sees another possibilty my current hope is it on the amp or the Marantz fixes the issue.
 
TLS Guy

TLS Guy

Seriously, I have no life.
I sympathize with you. Getting a system quiet is one of the biggest problems in equipment installation and design.

Unfortunately as you have found out ground loops and HDMI are a big problem, as loops can be external and in the equipment due to poor ground plane design.

However my thoughts on all this has evolved over time. Not all buzzes and hums are ground loops any more, or at least not entirely. Of equal if not more importance is RF interference which as exploded as a cause. The principal culprits are LED light bulbs and especially their associated dimmers. The issue is the huge rise of household discontinuous loads as the real underlying cause. Older homes really aggravate the problem because of older code standards, which did not address this issue and other factors.

Anyhow, all these causes of noise multiply exponentially with system complexity.

We have grandchildren living with us until tomorrow, but as soon as I get a chance I will go into this very complex issue in more detail. It never was simple and it is now a huge and ever expanding problem.
 
WaynePflughaupt

WaynePflughaupt

Audioholic Samurai
This is basically a process of elimination exercise. Start with the receiver and amp connected. Add components one at a time and see where the noise starts. Might not hurt to have a spare AVR and amp on hand to verify the status of the main ones, but you could try connecting the speakers directly to the Marantz to quantify the amp.

TLS Guy makes some great points. You might be needing a dedicated circuit(s) for your gear.

Regards,
Wayne A. Pflughaupt
 
TLS Guy

TLS Guy

Seriously, I have no life.
We had a request for advice on a guy building a pretty complex AV room in new home construction.

Here is some of the advice I gave him on this issue. Basically this is now a huge subject that actually warrants a text book of several hundred pages. It is a book I probably should write but doubt I will.

Here is what I wrote to him.

You need to properly plan your house grounding and equipment grounding. Earth loops that create hum and buzz are the curse of AV systems. With all the channels now this becomes of primary importance. A buzz formerly hardy heard on a two channel system becomes a roar with 11 channels and a sub or two doing it.

Ground loops are caused by resistances between grounds.

Now local electrical codes vary. Some require a ground to the water system and grounding rods. This sets you up for trouble right away.

Fortunately here in Eagan a ground to the water supply is all that is required. One ground is good, more, trouble.

So I supervised a massive cable to the water entry and then a massive cable to the panel. There are two panels a main and a large sub distribution panel. The panels are opposite sides of the same wall. Again these are linked with a large braided copper cable.

The racks in the chase are all linked with heavy copper cable and bonded with it back to the panel. The plug mold on the rack was bonded to the racks as was also the Comcast cable.

Now cable and satellite systems are a particular problem. They seem to come with inherent ground loops and despite good practice and following code, which I supervised there was a very low level buzz with the Comcast TV box connected. So I did have to isolate this ground with transformer. After that all 18 amp channels and the 11 speakers are dead quiet.

So pay attention to your grounding plan and ground plane.

Another issue is to make sure you use big enough gauge wire commensurate with your speaker impedance and length of the runs. I suspect you will have long runs and if so recommend 10 AWG Belden cable available from parts express. My AV room has 600 ft of this cable in conduit.

If you have HDMI runs longer than 25 feet, you will need either a boosted cable or a hybrid optical copper one. I recommend the later although more expensive. I also advise powering the cables from and external supply and not from the HDMI port.

This is the issues I can think of for now, but I suspect there are others.

Yes, there is one other issue I omitted to warn you about, and that is LED light bulbs and dimmers.

LED light bulbs and especially the dimmers radiate a lot of RF interference, which is another potent source of buzzing in AV systems.

Now you want to specify Lutron Maestro dimmers. These have the lowest RF emissions by far. Having said that keep the wiring off each dimmer limited. I did not allow lighting circuits to be shared with wall outlets. As far as possible I kept each dimmer on its own circuit.

Despite that I still had one issue. Some LEDs interfere with each other.

There are three LED fixtures on our stairway. On the other side of the landing dimmer was the dimmer for the family room lights. They were on the same circuit. Well when the stair lights and family room lights were both on, the family room lights flashed, the dimmers emitted noise right out of the switches and the RF really created a buzz in the studio. After a Google search I found this was a known issue with some LED combinations on the same circuit. We could only solve it by fishing another circuit from the panel so the stair and family room light were on different circuits. Then we had peace and quiet.

In the meantime it would be really helpful to me if I knew that date your house was constructed. This will have big impact on what I have to say and he lengths you may have to go to to solve the problem.
 
P

Pike44

Enthusiast
This is basically a process of elimination exercise. Start with the receiver and amp connected. Add components one at a time and see where the noise starts. Might not hurt to have a spare AVR and amp on hand to verify the status of the main ones, but you could try connecting the speakers directly to the Marantz to quantify the amp.

TLS Guy makes some great points. You might be needing a dedicated circuit(s) for your gear.

Regards,
Wayne A. Pflughaupt
If I unplug both the HDMI monitor out running to the projector and the HDMI in from the Control4 EA-3 Controller, the hum/buzz completely stops even with them still powered. I could possibly move the Control4 to a different receiver which would leave the projector HDMI connection as my only issue to solve. Before the amp everything worked no issues wired directly into the Marantz but I moved from a 7.1 to a 7.1.4 so I moved my front 3 to the amp.
I just tested with my previous receiver Elite SC-502 and it duplicated the exact issue the Marantz is having. Amp connected to AVR no issue. As soon as I add the projector HDMI Binary B6A (powered HDMI) the hum/buzz is back regardless of plugged in and unplugged. Same goes for removing it and adding the Control4 standard Binary HDMI cable. So regardless of the AVR, it seems something is happening between the amp and these 2 HDMI connections.
Not sure what I can do right now but have a new tower arriving Thursday so I will try to separate, clean up cords and regroup components as much as possible that might help with what TLS Guy mentioned. I have the HumX arriving Friday which I figured I'd try with the the amp to see if that does anything. I keep going back to the thought if the issue happens with everything powered down, there has to be something with adding the amp and either of those HDMI inputs especially since it happens just on the front 3, but if I add the 12v trigger between the amp and AVR it then reproduces this issue across all 11 channels with the front 3 buzz louder than without the 12v trigger attached.
 
P

Pike44

Enthusiast
We had a request for advice on a guy building a pretty complex AV room in new home construction.

Here is some of the advice I gave him on this issue. Basically this is now a huge subject that actually warrants a text book of several hundred pages. It is a book I probably should write but doubt I will.

Here is what I wrote to him.

You need to properly plan your house grounding and equipment grounding. Earth loops that create hum and buzz are the curse of AV systems. With all the channels now this becomes of primary importance. A buzz formerly hardy heard on a two channel system becomes a roar with 11 channels and a sub or two doing it.

Ground loops are caused by resistances between grounds.

Now local electrical codes vary. Some require a ground to the water system and grounding rods. This sets you up for trouble right away.

Fortunately here in Eagan a ground to the water supply is all that is required. One ground is good, more, trouble.

So I supervised a massive cable to the water entry and then a massive cable to the panel. There are two panels a main and a large sub distribution panel. The panels are opposite sides of the same wall. Again these are linked with a large braided copper cable.

The racks in the chase are all linked with heavy copper cable and bonded with it back to the panel. The plug mold on the rack was bonded to the racks as was also the Comcast cable.

Now cable and satellite systems are a particular problem. They seem to come with inherent ground loops and despite good practice and following code, which I supervised there was a very low level buzz with the Comcast TV box connected. So I did have to isolate this ground with transformer. After that all 18 amp channels and the 11 speakers are dead quiet.

So pay attention to your grounding plan and ground plane.

Another issue is to make sure you use big enough gauge wire commensurate with your speaker impedance and length of the runs. I suspect you will have long runs and if so recommend 10 AWG Belden cable available from parts express. My AV room has 600 ft of this cable in conduit.

If you have HDMI runs longer than 25 feet, you will need either a boosted cable or a hybrid optical copper one. I recommend the later although more expensive. I also advise powering the cables from and external supply and not from the HDMI port.

This is the issues I can think of for now, but I suspect there are others.

Yes, there is one other issue I omitted to warn you about, and that is LED light bulbs and dimmers.

LED light bulbs and especially the dimmers radiate a lot of RF interference, which is another potent source of buzzing in AV systems.

Now you want to specify Lutron Maestro dimmers. These have the lowest RF emissions by far. Having said that keep the wiring off each dimmer limited. I did not allow lighting circuits to be shared with wall outlets. As far as possible I kept each dimmer on its own circuit.

Despite that I still had one issue. Some LEDs interfere with each other.

There are three LED fixtures on our stairway. On the other side of the landing dimmer was the dimmer for the family room lights. They were on the same circuit. Well when the stair lights and family room lights were both on, the family room lights flashed, the dimmers emitted noise right out of the switches and the RF really created a buzz in the studio. After a Google search I found this was a known issue with some LED combinations on the same circuit. We could only solve it by fishing another circuit from the panel so the stair and family room light were on different circuits. Then we had peace and quiet.

In the meantime it would be really helpful to me if I knew that date your house was constructed. This will have big impact on what I have to say and he lengths you may have to go to to solve the problem.
House was just completed in July of 2019. Sorry if this is a dumb question, but if everything ran fine with no issues prior to the amp, would just adding the amp cause issues such as the ones I am having without the culprit being the amp? I'm really confused currently how those two HDMI cords are causing the noise despite all components for them being powered down minus the amp to the front 3 speakers. With those 2 both unplugged I go back to no issue with the amp hooked up or if I disconnect the amp to the Marantz the issue goes away.
 
TLS Guy

TLS Guy

Seriously, I have no life.
House was just completed in July of 2019. Sorry if this is a dumb question, but if everything ran fine with no issues prior to the amp, would just adding the amp cause issues such as the ones I am having without the culprit being the amp? I'm really confused currently how those two HDMI cords are causing the noise despite all components for them being powered down minus the amp to the front 3 speakers. With those 2 both unplugged I go back to no issue with the amp hooked up or if I disconnect the amp to the Marantz the issue goes away.
It certainly could. What I would do is this. First I would bond the chassis of the power amp and Marantz with heavy gauge bonded copper. Really is is best when the ground is at the preamp or pre/pro. You want to keep this as your only ground. So bond the Marantz tightly to your house ground, again with heavy gauge copper. Once you have the power amp bonded to the Marantz then lift the power amp ground with a cheater plug.

Now bond the controller and the projector you your Marantz again with 1/4" braided copper about a 1/4" in diameter. This will make the classic star cluster ground which I think is the best grounding system.

If you have hum or buzz after that it is almost certainly RF. If that is the case see if it stops switching off all light dimmer circuits at the panel. If you are not using Lutrom Maestro dimmers then RF is almost certainly part of the problem. LEDs plus dimmers makes quieting systems very difficult to say the least. I did not allow any sharing of lighting and AC outlets. I kept all LED light wiring as short as possible and no daisy chains. My HDMI runs to the TV in steel conduit which bonds the TV grounding to the system. All this has paid off as I have a super quiet system. I spent a lot of time planning the whole house electrical system and not just the AV systems.
 
P

Pike44

Enthusiast
It certainly could. What I would do is this. First I would bond the chassis of the power amp and Marantz with heavy gauge bonded copper. Really is is best when the ground is at the preamp or pre/pro. You want to keep this as your only ground. So bond the Marantz tightly to your house ground, again with heavy gauge copper. Once you have the power amp bonded to the Marantz then lift the power amp ground with a cheater plug.

Now bond the controller and the projector you your Marantz again with 1/4" braided copper about a 1/4" in diameter. This will make the classic star cluster ground which I think is the best grounding system.

If you have hum or buzz after that it is almost certainly RF. If that is the case see if it stops switching off all light dimmer circuits at the panel. If you are not using Lutrom Maestro dimmers then RF is almost certainly part of the problem. LEDs plus dimmers makes quieting systems very difficult to say the least. I did not allow any sharing of lighting and AC outlets. I kept all LED light wiring as short as possible and no daisy chains. My HDMI runs to the TV in steel conduit which bonds the TV grounding to the system. All this has paid off as I have a super quiet system. I spent a lot of time planning the whole house electrical system and not just the AV systems.
Thanks, I'll try to wrap my head around this. My biggest hurdle would be getting the projector bonded to the Marantz as the AVR is in a media closet and the projector is wired above in the attic about 20-30 feet away. For the dimmers all I know is they are controlled via Control4. Probably won't be able to start on this until the new media tower is in since not worth separating and re-doing everything until it is in. So disappointing as the D-Sonic amp and the added 4 speakers really brought my setup to life but the hum gets to me anytime a scene goes quiet.
 
lovinthehd

lovinthehd

Audioholic Jedi
If you have a cheater plug around you can at least see if lifting the ground will make a difference.....not a permanent solution but....
 
J

JStewart

Audioholic Intern
It certainly could. What I would do is this. First I would bond the chassis of the power amp and Marantz with heavy gauge bonded copper. Really is is best when the ground is at the preamp or pre/pro. You want to keep this as your only ground. So bond the Marantz tightly to your house ground, again with heavy gauge copper. Once you have the power amp bonded to the Marantz then lift the power amp ground with a cheater plug.

Now bond the controller and the projector you your Marantz again with 1/4" braided copper about a 1/4" in diameter. This will make the classic star cluster ground which I think is the best grounding system.

If you have hum or buzz after that it is almost certainly RF. If that is the case see if it stops switching off all light dimmer circuits at the panel. If you are not using Lutrom Maestro dimmers then RF is almost certainly part of the problem. LEDs plus dimmers makes quieting systems very difficult to say the least. I did not allow any sharing of lighting and AC outlets. I kept all LED light wiring as short as possible and no daisy chains. My HDMI runs to the TV in steel conduit which bonds the TV grounding to the system. All this has paid off as I have a super quiet system. I spent a lot of time planning the whole house electrical system and not just the AV systems.
Sorry to interrupt, but @TLS Guy do you have a suggestion to attach the 1/4” braided wire to a chassis?
 
P

Pike44

Enthusiast
I tied a ground from the amp to the receiver and no difference. Won't have a chance to try to tie to the projector until new tower is setup but I did tie to the Control4 via a screw on the chassie (not sure if that's correct, but didnt see other option) and noticed no difference .
I did notice while testing more the HDMI to the Control4 EA-3 Controller throws the hum/buzz sound about twice as far distance wise from the speaker than the projector HDMI. When both are plugged in it throw a little further. Volume on the AVR does not effect any difference. At this point starting to wonder if the RF interference suggestion might be more of the cause. Hoping that some re-arrangement and separation with the new tower might help. I did find out my dimmers and media room blackout shade run off a Lutron Caseta Wireless smart bridge .
I am calling my previous AV company tomorrow and making sure I can switch over the Control4 to the downstairs living room receiver with no issues as I honestly am not sure what that HDMI is feeding to my media room AVR. That would at least get the biggest offender off my Marantz. I did try changing out the HDMI cords for these 2 devices and that made no difference either. Still confusing to me if everything in the media closet is disconnected from the power except the amp, I still get the hum/buzz being added when either of those 2 HDMI connections are made. Starting to wonder if it would be worth trying a different set of RCA cords than the SVS ones I currently have.
 
P

Pike44

Enthusiast
Seriously doubt the SVS rca cables failed....
I secretly hope that would be the issue as then I could be done with this ordeal, but I agree from SVS reputation that this is probably extremely unlikely. Just to cover my bases, I'm probably just going to pick up 1 set from Blue Jeans Cables and connect it to a different channel than the SVS to ensure there is no difference. Worst case I am out the shipping cost and can return afterwards.
 
lovinthehd

lovinthehd

Audioholic Jedi
I secretly hope that would be the issue as then I could be done with this ordeal, but I agree from SVS reputation that this is probably extremely unlikely. Just to cover my bases, I'm probably just going to pick up 1 set from Blue Jeans Cables and connect it to a different channel than the SVS to ensure there is no difference. Worst case I am out the shipping cost and can return afterwards.
Or try cables from the new guy posting in the forums, James @afford-hifi. I'd just get Amazon basics or Mediabridge or build my own....
 
R

rbl

Audioholic Intern
I would swap out the HDMI cable and I would also check the polarity on any/all outlets you are using with a proper tester.

The HDMI cable is your common link as I read it. Try forcibly wiggling it and see if the hum is interrupted.

The hum is not necessarily a ground loop and can be simple feedback.
 
P

Pike44

Enthusiast
Just an update on my issue. After trying everything I could manage (power conditioners, new cords, re-wiring/moving everything in the rack, trying to ground, fiber optic HDMI replacements, HumX and lifting grounds) the only thing that truly solved this issue without possibly violating electric codes (HumX and cheater plug for the amp) was buying the Jensen Iso-Mac CI-1RR and CI-2RR for between the AVR and amp. Although an espensive route, this killed the hum and everything is working great.
 
C

CoryW

Audioholic
The only thing that jumps at me is the projector. Try plugging it into the same outlet as the rest of the equipment. The plug it’s using might be on the opposite phase from the other gear.

If that doesn’t work, I’d try ditching the surge protector and trying a straight power strip.

Other culprits for ground loops are cable TV service feeds and satellite feeds that are grounded somewhere besides the main house electrical earth ground stake.

Regards,
Wayne A. Pflughaupt
Yup on cable. I had to buy a ground loop eliminator for RG to remove a pesky hum. I’m luck to have moved to balanced connections that stopped all this silly stuff.
 

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