Loud buzz through the speakers. Marantz Cinema 30

[highfigh]

I think you theory is very unlikely. I would bet that Cinema 30 has an incompetently designed ground plane.

All those amps are going to take gobs of current. I would bet that the grounding wires are just on small wire snap in connectors. So that is producing ground plane gouging and hum, when connected to a device that is actually true ground.

In a unit like that the ground plain should be constructed from massive copper cables or wide copper board line circuits on the boards. Having designed quite a few ground planes, I can tell you it only takes a minute voltage on a ground line to cause one Hell of a hum.

These AVRs with all those power amps for Atmos are the daftest products to ever see the light of day. I predict they will bring nothing but grief.

If you're speculating on the ground wire size, try to find out for sure.

A lot of equipment has ground wires screwed to the main chassis pan- what happens on the board side is less important, as long as they end with an adequate ring terminals, star washer and the gauge is more than what's required. Plug in connectors (Euro/Phoenix, Molex, etc) are OK, but not when the current creates hot terminal connections.

We need a way to communicate with the engineering departments- that's the only way this can be changed.

 

[Tankini]

Do you use a cable TV provider for TV, internet and/or phone? If so, make sure the coax is grounded near the point where it enters the house/building. This should be passing through a grounding block at the electrical meter box or if it enters farther from the meter box, it should be grounded to a cold water pipe or the breaker panel. If the building has PEX or some other non-conductive plumbing, this is difficult but IT IS REQUIRED by the National Electrical Code in articles 770, 805, 810, 820, 830 and 840. It's also covered by ANSI/TIA-607-B.

Cable installers frequently neglect to ground the cable feed and it can not only cause this kind of noise, it's a safety hazard- NEC REQUIRES grounding-it's not optional and if it's not grounded, the provider should repair this code violation.

Disconnect the cable at the modem or cable box and if the noise stops, call the provider and demand that they make it right.

If they refuse, you have at least two options- change providers or install a DC block on the cable, but the latter won't work if the cable company needs a direct connection to their system.

Absolutely correct in your statement. I could not have stated any better. I had a hum problem and it was my coaxial from Cox Cable causing the issue of a very loud hum, wasn't grounded outside. Drove me nuts trying to isolate it, was the last thing I disconnected and the hum went away immediately.

 

[DigitalDawn]

Absolutely correct in your statement. I could not have stated any better. I had a hum problem and it was my coaxial from Cox Cable causing the issue of a very loud hum, wasn't grounded outside. Drove me nuts trying to isolate it, was the last thing I disconnected and the hum went away immediately.

We see this all the time. This is what we use to fix it: https://www.jensen-transformers.com/product/vrd-1ff/

 

[Tankini]

We see this all the time. This is what we use to fix it: https://www.jensen-transformers.com/product/vrd-1ff/

I called Cox they sent out a tech to ground their cable. That was back in 2012. Before I installed a in-line filter that stop almost all of the hum. Could still hear the hum but had to get close to my subs and speakers to hear it. After Cox came out and Install the ground outside, hum went away completely. I remove the filter.

 

[highfigh]

Absolutely correct in your statement. I could not have stated any better. I had a hum problem and it was my coaxial from Cox Cable causing the issue of a very loud hum, wasn't grounded outside. Drove me nuts trying to isolate it, was the last thing I disconnected and the hum went away immediately.

Did you ground it? That's required. The block is a bandaid, but it can also negatively affect the performance of cable TV equipment because they often use a direct connection for data.

I helped with an apartment AV/Data installation in Chicago and when we turned the TV on, we saw hum bars scrolling up the screen and hum from the audio. My friend asked if I happened to have a DC block and after I went down to the van to grab it, the problem was gone. We told the owners of the place to contact the provider to ground the feed and check out the system and they did- a couple of weeks later, the wife called my friend to tell him that the hum had returned, so he asked if there was a small barrel-shaped part on a shelf. It was there, because that tool had removed it.

I guess she should have slipped him some cash, TO GET HIM TO DO HIS JOB.

 

[Tankini]

Did you ground it? That's required. The block is a bandaid, but it can also negatively affect the performance of cable TV equipment because they often use a direct connection for data.

I helped with an apartment AV/Data installation in Chicago and when we turned the TV on, we saw hum bars scrolling up the screen and hum from the audio. My friend asked if I happened to have a DC block and after I went down to the van to grab it, the problem was gone. We told the owners of the place to contact the provider to ground the feed and check out the system and they did- a couple of weeks later, the wife called my friend to tell him that the hum had returned, so he asked if there was a small barrel-shaped part on a shelf. It was there, because that tool had removed it.

I guess she should have slipped him some cash, TO GET HIM TO DO HIS JOB.

The Cox Tech came out to my apartment a few days later. Told him the issue, I fried up my system, at that time I had a 5 channel Amp, a 2 channel Amp, two 12" subs, a Parasound Prepro all paired up to a Onkyo THX-NR818 AVR with Polk LSi-15's, LSi center and LSiFX surrounds. As soon as I turned on my system the hum could be heard with that Barrel filter still in-line we both could hear the hum Especially after cranking the volume up to halfway with no Source playing. As he was standing there I Disconnected the cable from my television hum went away.

Tech went outside to the Cox box that was attached to the building and discovered cable wasn't grounded. Which I knew already. He went back to his Cox van came back with a Two foot ground bar a clamp and some copper wire. Hammered the ground bar into the ground, about two inches sticking up out the ground, clamped the copper wire to the ground bar, looked like about 12 gage. Grounded it to a ground plate in the Cox cable box. Took that Barrow filter out of service and Voila no more hum. Took him about 30 minutes of work.

 

[TLS Guy]

We see this all the time. This is what we use to fix it: https://www.jensen-transformers.com/product/vrd-1ff/

Very bad advice.

I don't need one, as I know how to engineer my systems and house. But I tried one of those to see if I could recommend them. Cable systems to not work properly with those devices. They stop control especially of DVR service and make a mess of the control functions. So I never recommend them with ground loop buzz problems. You should not either.

DO NOT USE THOSE.

 

[TLS Guy]

The Cox Tech came out to my apartment a few days later. Told him the issue, I fried up my system, at that time I had a 5 channel Amp, a 2 channel Amp, two 12" subs, a Parasound Prepro all paired up to a Onkyo THX-NR818 AVR with Polk LSi-15's, LSi center and LSiFX surrounds. As soon as I turned on my system the hum could be heard with that Barrel filter still in-line we both could hear the hum Especially after cranking the volume up to halfway with no Source playing. As he was standing there I Disconnected the cable from my television hum went away.

Tech went outside to the Cox box that was attached to the building and discovered cable wasn't grounded. Which I knew already. He went back to his Cox van came back with a Two foot ground bar a clamp and some copper wire. Hammered the ground bar into the ground, about two inches sticking up out the ground, clamped the copper wire to the ground bar, looked like about 12 gage. Grounded it to a ground plate that the cable was coming in from the service box from the poll. Took that Barrow filter out of service and Voila no more hum. Took him about 30 minutes of work.

You were lucky as you now have two grounds. Code requires that those system be grounded to your electrical service, preferably at the panel.

I redid the ground on my cable entry and really made sure of it.

 

[Tankini]

You were lucky as you now have two grounds. Code requires that those system be grounded to your electrical service, preferably at the panel.

I redid the ground on my cable entry and really made sure of it.

I asked him that, his answer was the Cox box was closer. The panel and the electric meter was behind a wooden fence and the service panel into that apartment was on the 2nd floor. I don't believe that Cox cable was ever grounded.

 

[highfigh]

Very bad advice.

I don't need one, as I know how to engineer my systems and house. But I tried one of those to see if I could recommend them. Cable systems to not work properly with those devices. They stop control especially of DVR service and make a mess of the control functions. So I never recommend them with ground loop buzz problems. You should not either.

DO NOT USE THOSE.

The link shows "Important Note: The VRD-1FF is NOT suitable for use with RG11 cable or as an isolator for satellite dish systems." just above the link to the manual.

 

[highfigh]

I asked him that, his answer was the Cox box was closer. The panel and the electric meter was behind a wooden fence and the service panel into that apartment was on the 2nd floor. I don't believe that Cox cable was ever grounded.

They don't know what they don't know.

That guy doesn't understand the NEC info- I would call COX repair department and explain that you know this is all covered by the National Electrical Code BICSI and if necessary, that you can provide a link to the Article 800 and the BICSI article on grounding and bonding.

NEC-

https://www.ecmag.com/magazine/articles/article-detail/codes-standards-communications-systems-grounding-rules-article-800-provides-specific

BICSI-

https://www.bicsi.org/docs/default-source/conference-presentations/2017-mea-uae/grounding-and-bonding.pdf?sfvrsn=3112558d_2

 

[DigitalDawn]

Very bad advice.

I don't need one, as I know how to engineer my systems and house. But I tried one of those to see if I could recommend them. Cable systems to not work properly with those devices. They stop control especially of DVR service and make a mess of the control functions. So I never recommend them with ground loop buzz problems. You should not either.

DO NOT USE THOSE.

We have had good experiences with this filter. It's a great temporary fix until the cable company fixes the ground.

 

[TLS Guy]

We have had good experiences with this filter. It's a great temporary fix until the cable company fixes the ground.

Glad you have never done any work in our place!

 

[Tankini]

They don't know what they don't know.

That guy doesn't understand the NEC info- I would call COX repair department and explain that you know this is all covered by the National Electrical Code BICSI and if necessary, that you can provide a link to the Article 800 and the BICSI article on grounding and bonding.

NEC-

https://www.ecmag.com/magazine/articles/article-detail/codes-standards-communications-systems-grounding-rules-article-800-provides-specific

BICSI-

https://www.bicsi.org/docs/default-source/conference-presentations/2017-mea-uae/grounding-and-bonding.pdf?sfvrsn=3112558d_2

Cox had a monopoly on this city for over 40+ years. Horrible service, very expensive Cox internet 250 mbps 1T 138 a month. I was lucky if I got 90mbps up or down. I'm with AT&T fiber Internet, 500mbps up/down 35 bucks a month no contract Unlimited data.. Cox internet would be dropout 3-5 times a month sometimes within days apart. Cox loves to hit their customers with a bunch of fees, lock you into bundle deal contracts. I don't pay a Monthly fee for the router/modem with AT&T. Cox changes 8.99 a month.

But that issue I had was over 12 years ago in that Townhome.

 

[DigitalDawn]

Glad you have never done any work in our place!

My goodness, you really go out of your way to insult me. I'm not sure why. Not sure what I might have said in the past to tick you off, but whatever it was I apologize.

I have been doing this work for a while I've been a custom installer since 2001 and a CE writer (with 2000 articles and reviews) since 1984. Honestly, on the Comcast cable system we have here in Palm Beach County, Florida, the Jensen transformers work wonderfully for ground loop issues. Never once had a problem.

 

[highfigh]

My goodness, you really go out of your way to insult me. I'm not sure why. Not sure what I might have said in the past to tick you off, but whatever it was I apologize.

I have been doing this work for a while I've been a custom installer since 2001 and a CE writer (with 2000 articles and reviews) since 1984. Honestly, on the Comcast cable system we have here in Palm Beach County, Florida, the Jensen transformers work wonderfully for ground loop issues. Never once had a problem.

Do you only use the isolators, or do you also make sure the service is grounded according to the articles I posted?

Have you ever measured the voltage on a Cable TV feed, referenced to ground? If you haven't, you should. I reached behind my cable box to disconnect the cable because the box needed to be replaced and when the F connector had come out, I got a pretty good tingle in my arm because the power cord was still connected. Once the cable had been grounded at the service entrance, the cable was no longer electrically 'hot'.

 

[highfigh]

Cox had a monopoly on this city for over 40+ years. Horrible service, very expensive Cox internet 250 mbps 1T 138 a month. I was lucky if I got 90mbps up or down. I'm with AT&T fiber Internet, 500mbps up/down 35 bucks a month no contract Unlimited data.. Cox internet would be dropout 3-5 times a month sometimes within days apart. Cox loves to hit their customers with a bunch of fees, lock you into bundle deal contracts. I don't pay a Monthly fee for the router/modem with AT&T. Cox changes 8.99 a month.

But that issue I had was over 12 years ago in that Townhome.

MKE started with Warner-Amex in the city, but they didn't reach agreement with the surrounding areas, so they signed up with Vaicom and IIRC, Hughes. Viacom used two cables and after I had gone to work at a store that was more video-oriented, people would call to ask how they could watch one channel and record another, even though they didn't understand. Someone created a diagram and a parts package that we sold, including splitters and a video switch. Eventually, Warner-Amex became Time Warner and they gobbled up all of the competition but even then, the basic package was $9.95/month. I know people whose TV only part of the bill is more than $200, now. Ridiculous!

 

[Tankini]

Do you only use the isolators, or do you also make sure the service is grounded according to the articles I posted?

Have you ever measured the voltage on a Cable TV feed, referenced to ground? If you haven't, you should. I reached behind my cable box to disconnect the cable because the box needed to be replaced and when the F connector had come out, I got a pretty good tingle in my arm because the power cord was still connected. Once the cable had been grounded at the service entrance, the cable was no longer electrically 'hot'.

Thank for Mentioning this! That is Exactly what happened to me,
which led me to believe it was a cable issue I got zapped!

"I got a pretty good tingle in my arm because the power cord was still connected. Once the cable had been grounded at the service entrance, the cable was no longer electrically 'hot'."
[/QUOTE]

 

[DigitalDawn]

Do you only use the isolators, or do you also make sure the service is grounded according to the articles I posted?

Have you ever measured the voltage on a Cable TV feed, referenced to ground? If you haven't, you should. I reached behind my cable box to disconnect the cable because the box needed to be replaced and when the F connector had come out, I got a pretty good tingle in my arm because the power cord was still connected. Once the cable had been grounded at the service entrance, the cable was no longer electrically 'hot'.

Fortunately, I haven't experienced the high-voltage issue you mentioned, but we absolutely, always test the voltage, just in case. The Jensen transformer is a temporary stop-gap (my tech always has one in his truck), and we call the cable provider to come out to fix the grounding issue.

 

[highfigh]

Fortunately, I haven't experienced the high-voltage issue you mentioned, but we absolutely, always test the voltage, just in case. The Jensen transformer is a temporary stop-gap (my tech always has one in his truck), and we call the cable provider to come out to fix the grounding issue.

I learned a lot form Bill Whitlock when he was at CES and later, at CEDIA, although I remembered what he said the first time I heard him. Still it was a good refresher.

I like Jensen products, but wouldn't leave something like this in place with thoughts that it's a permanent solution. Cable company thinking, notwithstanding.