Noise coming from subwoofers and centre channel

Put the projector on the same circuit

Hi,

the projector and the processor are on the same circuit…

This might be overly simplistic, but what about just trying some cheater plugs?

- Turn off subwoofers and see if noise is coming from the center

- Turn on one subwoofer at a time and see when the noise starts

- Unplug/Replug the subwoofer cables, try a different cable

- Is there a PC on a UPS or something plugged into the same line. Turn that off

etc. etc, (narrow down on what’s creating the noise by process of elimination)

If the sound shows up only on the center channel and subs (not the fronts??), i am also inclined to believe that it may be something with the av processor/receiver. Check all cable connections, check for sht failing cables, make sure everything’s plugged in where it’s supposed to be, etc.

Good evening,

yes the cheater plug are on my list.

What i did tonight is to disconnect all my rack audio, a nightmare as i have many electronics…

I only have connected my 2 channel setup, front Dunlavy SC-4, 2 funk subwoofer, Mola Mola Tambacqui, antipodes K50 and finally Hegel H590.

For the moment, good news, complete silence, no hmm, no hiss. 

i will continue tomorrow, i will integrate my AVR, player, projector, processor one by one.

What do you think guys IFI gnd defender?

Thanks for all your comments.

I used to have a complicated multichannel rig and multiple stereo rigs all in one room (until i finished/managed to move all stereo gear to another room. It was indeed a nightmare looking behind multiple racks with heaps of sht, gear and cables everywhere.

I was going to suggest could it be the projector has another ground path??  Try turning it on without any video cables attached.

@vampat  Your trouble shooting is in the pipe 5x5. Nice system.

Hi,

Well, I have something new, I continued my tests. Here are my findings.

I opened all the devices of my 2 channel audio system (Tambacqui, K50 and Hegel H590 complete silence.

Then, I connected the Madvr Envy video processor and nothing complete silence

Then I integrated my Hegel C55 5 channel amplifier, I only connected the center. Still complete silence. Now I integrate the arcam AVR-30 receiver, we can hear a slight electrical noise in the center channel and a slight rumble in the subwoofers.

Finally,  there it is, I connect an HDMI cable between the processor and the receiver and an HDMI cable between the receiver and my Zappiti player, the noise is really louder in the subwoofers and the center channel.

So, I understand that my problem occurs when a signal goes through the HDMI, what do you think?

Should I try a cheater plug and connect the receiver?

Thanks.

I did another test and connected my center directly into the receiver. Now the noise disappears in the center compared to when connected in the external amplifier. However, the noise is still present in the subwoofers... All my devices are connected on the same circuit, it's a circuit just for my electronic devices.

OP: 

It does sound like a ground loop is forming.  If you disconnect the video cable from your projector does the noise go away? 

Nice detective work, and at least at this point there’s a loop that involves the AVR and/or amp. If it’s me I’d try the simplest thing first that’d be a cheater plug on the AVR, then on the amp, and then on both (if necessary) and see what happens. You could also consider contacting the fine folks at Hegel as they may give you a very quick and effective solution rather than spending time/$ trying different things. I’d be interested to hear what you find.

Okay now, I removed the two HDMI cables on the processor, projector out and Zappiti player in, the noise disappeared completely. I reconnected the center to the external amplifier and there is no noise either. So it’s the video part that causes this problem. First time in 2 decades that this has happened to me...

I’m going to buy two 3 to 2 sockets, it’s not expensive.

I hope it’s not too risky to use such a socket.

I will send an email to Hegel for their opinion. thanks for the advice

Good evening, Nice testing evening!

1-I installed a 3 two 2 pong on the AVR: no change :-(

2- I added another adapter to the Hegel external amplifier: it really doesn't like the socket, very loud buzz :-(

3-I remove the Hegel one and put it on my Madvr Envy processor: I was starting to get discouraged, I put my ears on the central channel and my subwoofers, I still hear a slight buzz and crackling but I would say 70% less loud ... :-)

4- I say to myself, I'm going to add one to my JVC NZ9 to see.... and yes there is NO MORE NOISE!!!!!!!

Does it exist another solution that would have the same result as this electrical outlet? I find it strange to connect a small piece of plastic to a fairly high-end cable. In addition, is this a risk for my projector and processor? Can performance be affected? it is still 2 products worth 45K.....

IFI GND defender?

Thanks again for your good advice, I really appreciate it, thank you all

It is risky to use a cheater plug.  The correct answer here is you want an HDMI isolator, and one way to achieve this isolation is to use HDMI to Ethernet converters...

https://amzn.to/3OyueZU

PS - I did find direct HDMI to optical isolators at around $750 a pair, so the options above are a lot cheaper.

Also, double check you don't also have a coaxial cable coming in somewhere, those are often hum sources, and relatively easy to fix.

yes, in fact, there is an unconnected coaxial cable, which was used by a former TV provider several years ago. Do you think there may still be signal even though I haven't been with this provider for years and have never had a ground problem in 10 years?

OP: The coax only matters if it’s plugged into a device in your rack and can create a new ground path. Coaxial ground loop eliminators are cheap and plentiful. Honestly everyone should use them just in case.

Having an antenna or cable TV cable grounded outside your home by a grounding block is code,and not by itself a problem. The problem is when that cable is connected inside to a set top box and that set top box is connected to your stereo. The outer shield in the coax now creates a very long and separate ground path.

By the way, we don’t have the same issues with Ethernet because Ethernet is inherently isolated. Mostly. For this reason we don’t have ground loops when your cable Internet is connected to devices inside via Ethernet.

PS - If the coax isn't used, make sure it's disconnected outside.  Even though there may be no equipment at the provider side that long coax can function as an antenna and bring in lightning surges into the home.  Leave the grounding block in place.

One thought — you didn’t mention if you’re using a power conditioner/surge protector, which I would hope you are given the cost of your system.  If so obviously the conditioner would be plugged into the wall with a 3-prong plug so wondering if then using a cheater plug on the projector is a non issue?  If you’re not using a power conditioner that’s definitely something to address, and depending on how its designed may also help alleviate your noise issue without a cheater plug.  Just some further thoughts FWIW and glad you’ve at least identified the culprit and gotten rid of the noise — that’s gotta be a huge relief!

Hi good afternoon,

I only use a powerbar. Here a link of my model. All my power cable are from Bis audio ( 3prong plug)

BIS Audio PowerBIS Maestro A/C Power Bar + AC20WG A/C Power Cord Review – NOVO Audio and Technology Magazine

Thank you for your findings. Indeed, I am happy to have made the discovery but I do not want to put my system and our security at risk....with the cheater plug...

Not quite sure where you are in your investigation.

If your system is connected to cable tv I will share I had a pretty obvious hum/buzz. 

What solved my problem entirely was connecting the following Jensen VRD-1FF IsoMax CATV Digital RF Isolator between my xfinity coax and the xfinity cable box needed to run my TV.

Jensen Iso-Max VRD-1FF 75 Ohm Inline Digital CATV Isolator Hum Eliminator (parts-express.com)

Note that the coax from outside is first split and one leg goes to the TV and the other to my modem/router.  This was only needed on the coax leg going to the xfinity cable box.

Hi,

No my system is not connected to any TV cable.

Thanks for sharing.

I only use a powerbar...I am happy to have made the discovery but I do not want to put my system and our security at risk....with the cheater plug...

But, your entire system already is at risk as you’ve got no surge protection and there are many here who’ve told tales of losing expensive equipment plugged into the wall.  I have a vey transparent Wiremold power strip, and when I wanted to add power conditioning and surge suppression I just got this and plugged my power strip into it and my whole system was protected on the relative cheap.  I still question if your power strip is plugged in with a 3-prong plug if the cheater plug makes any difference — I don’t know the answer but maybe someone like @erik_squires or someone else does.

https://www.usaudiomart.com/details/650064731-audience-adept-response-ar1p-power-conditioner/

FWIW.

I only use a powerbar...I am happy to have made the discovery but I do not want to put my system and our security at risk....with the cheater plug...

But, your entire system already is at risk as you’ve got no surge protection and there are many here who’ve told tales of losing expensive equipment plugged into the wall. I have a very transparent Wiremold power strip, and when I wanted to add power conditioning and surge protection I just got this and plugged my power strip into it and my whole system was protected on the relative cheap. I still question if your power strip is plugged in with a 3-prong plug if the cheater plug makes any difference — I don’t know the answer but maybe someone like @erik_squires or someone else does.

https://www.usaudiomart.com/details/650064731-audience-adept-response-ar1p-power-conditioner/

I suppose it’s also possible that installing a power conditioner may fix the problem with no cheater plug needed. FWIW.

I’m a huge fan of Furman power conditioners, but I can almost guarantee no conditioner will solve a ground loop problem, no matter how much you spend on it.

Cheater plugs will work, at a high safety risk. What you really want is to isolate the signal ground that causes the loop, not the AC ground.

While there’s nothing in a Furman or megabuck power conditioner that will solve a ground loop, moving all AC plugs to the same strip sometimes is a solution, but it’s not a matter of any circuitry but rather that the grounds are so close.

The OP has already moved everything to the same outlets.  He's pretty much demonstrated that what he needs is an HDMI isolator.

I tried an IFI defender socket this evening, without success, doesn't change anything.
 

All my electronics are on the same circuit, same powerbar.

The Audience Adept arp1 seems interesting at reasonable cost.

I still don’t have an answer that if the power strip is plugged in via a 3-prong plug and the projector is then plugged into the strip with a cheater plug if that’s still an issue.  If the power strip is grounded I don’t see why plugging a component into it with a cheater plug would be a problem as it’s already grounded through the power strip.  Am I missing something here?

I had what seemed to be connectivity issues with my Pioneer Elite AV receiver and the Elite plasma. 

Replacing the high quality HDMI cable with brand new modestly priced cable solved the problem. I don't think HDMI is very robust to begin with. 

Taking your trouble shooting a step further, star grounding, using a power strip into one receptacle and connecting each component one at a time. Plugging additional power strips into the first strip maintaining the single receptacle power source may reveal a grounding issue. 

@soix Yes, you are missing the reason the AC cable has a ground wire.  It's to trip the fuse.

The ground wire on equipment (amp, refrigerator, any) is there to ground the metal shell so in the event of a fault where the incoming hot shorts to the outer shell the current should flow through the ground wire in the power cord at a high enough rate to trip a breaker or fuse.  The idea is to trip the fuse before a person or pet touches it and electrocutes themselves.

The problem is signal ground wires (shields) can't safely conduct that much current leaving two bad options:

1.  High resistance, which leaves the chassis hot and dangerous

2.  Melts and causes a fire

That's why cheater plugs are in all cases not safe. 

Hi,

Yes my power strip is plug via 3 prong.

I did the test to plug the equipement one by one, the noise is really introduce when the projector and processor are in action.

OP:  Not sure how portable your projector is, but can you move it close and use a very short HDMI cable?  If that fixes the issue, a better (not more expensive) cable may be a good option.

No it is heavy (JVC-NZ9) it would be complicated...

Highly recommend buying a digital filter for your Cable wire leading into your cable box. Make sure you get one that's male female so you can just avoid using another wire. You can get them for about 10 to 20 bucks on Amazon. There was a recommendation made earlier for $75 isolator but that was crazy. @jetter .

Maybe the recommendation was for a really great isolator but the one I bought solved 90% of the problem. And my cable wiring to my house is grounded. Another problem I had was I have a tube amplifier and that inherently picked up a lot of hum versus solid state when I had one which had no hum.

You could always just buy a dog and forget about everything else.

OP: Well my recommendation of an HDMI isolator is still the best way to go, but another HDMI cable may help and be a cheap solution.

It would really only help if the ground was significantly better... so for sure dont' spend money on boutique cables.  Buy an affordable one that's as short as possible but looks well made.

For the HDMI isolator, how it would works. My HDMI is connected between my projector and processus and then, it to my AVR.

Where do we connect this isolator?

Thanks

The HDMI isolator seems to be very expensive more than 1000 $ CAD.

Also, i hope those isolator are compatible with Dolby atmos, HDR, 4K etc....

Could something like this possibly solve the problem?

FIBBR FIBBR Câble à fibre optique HDMI 8K 48 Gbit/s ultra haut débit 8 K 60 Hz 4 K 120 Hz 144 Hz HDR/eARC dynamique compatible avec PS5, Xbox Series X, PC, TV (5 m) : Amazon.ca: Électronique

OP:  Some of my recommendationsi were well under $100

I think most of the model are not 4K 120hz 60hz.

Here's one for $130