New LG 4K TV, terrible 60Hz buzz

[r042wal]

I just installed a new LG 65" 4K TV. As soon as I turn it on, I get terrible hum out of my SVC-2000 Pro sub. It connects back to my preamp with a 15' coax cable.
I have tried my Jensen isolation transformer but it does not seem to work.

I have an HEL 5GHz transmitter/receiver that I though I would give a try. Any opinions or suggestions? My old TV never had this issue

Thanks

 

[ozzy9832001]

Is the power cable attached or can you switch it out for a different one? Assuming the circuit isn't overloaded, probably bad shielding on some component on the TV.

 

[Doodski]

Is the power cable attached or can you switch it out for a different one? Assuming the circuit isn't overloaded, probably bad shielding on some component on the TV.

60 Hz shielding is not a likely fault. There is 60 Hz all around us as we chat and that does not get into the audio stream unless there is a bad ground. There is a ground fault somewhere in the system causing the audio stream to buzz at 60 Hz. (Because the ground reference is not present.)

 

[RayDunzl]

I just installed a new LG 65" 4K TV. As soon as I turn it on, I get terrible hum out of my SVC-2000 Pro sub. It connects back to my preamp with a 15' coax cable.

Does it hum with the coax disconnected and the TV on?

( I know, it's a dumb question, but...)

 

[r042wal]

Does it hum with the coax disconnected and the TV on?

( I know, it's a dumb question, but...)

No coax. Two HDMI and an an Ethernet. Thanks

 

[r042wal]

60 Hz shielding is not a likely fault. There is 60 Hz all around us as we chat and that does not get into the audio stream unless there is a bad ground. There is a ground fault somewhere in the system causing the audio stream to buzz at 60 Hz. (Because the ground reference is not present.)

The cord is permanently attached to the TV. I tried wrapping it around a 2" torroid ring but it did not make any difference

 

[Krusty09]

Do u have a cable box or a sat box? leave everything connected the way it is and just disconnect the coax going into the box from outside the house and see if the hum goes away. Both cable TV and satellite have there own ground structure that is not part of the house ground structure and a lot of times causes hum. Another quick test is if the sub is connected to another outlet in the house other then the one that the TV/AV/Stereo is connected to run an extension cord from the same outlet that the TV is connected to to the sub and see if that changes things as the outlets could be on different phases and cause hum as well.
If that doesn't do it then there are some other things to try later .

 

[AnalogSteph]

The first mistake probably was buying an LG TV, but I digress. As far as I can tell, they don't seem to be all that great in the quality and reliability department. Might be a matter of "you get what you pay for", of course.

The first thing I would look at and compare between the old and new TV is the mains cable. If that's one of these 2-prong jobs and your network cabling is UTP, the TV's mains filter may be dumping a bunch of leakage current into your audio ground because that connects to mains PE at the sub. If left floating, there may be so much common-mode voltage that it's taxing isolation transformer CMRR, giving the impression that the latter is not doing much. Or the problem is simply not where you thought it was (i.e. not a ground loop involving the sub connection itself).

I don't quite get your setup - what is handling the HDMI?

 

[r042wal]

My error, Amazon fire box connects to TV by HDMI. Local cable STB also connects to TV by HDMI. TV then connectes to McIntosh C48 by optical. Worked very well on my old Samsund 1024.

TV bought and purchased so I was hoping for TS suggestens, not *what" I should have or should not have bought. Please humor me lol Thanks