Audible Hum

[Zing]

A few days ago, I turned on my system and heard a buzzing sound immediately. That's never happened before so, as annoying as it was, I just dismissed it and attributed it to a temporary electricity anomaly. It hasn't gone away. So I thought I'd investigate.

The first thing I did was disconnect the coax cable from my cable TV box. The sound stopped. I reconnected the coax and then disconnected the HDMI cable from the cable TV box. The sound stopped again. I reconnected the HDMI and then disconnected the power cable from the cable TV box. The sound remained on.

Is this indicative of the infamous ground loop issue that plagues so many? If so, why did it just start a few days ago and not 7 years ago when I first got cable? Might it go away on its own in the near future or do I need to employ some ground loop corrective protocol?

 

[Towen7]

Check the grounding on the coax cable that serves the house. There cable company's line should meet your wiring at a barrel connector that is grounded at the same point that your homes electrical lines are. Also check that the home's grounding clamp is tight.

My techs work at houses every day and around 20% have loose or improperly terminated grounding clamps. We find coax loose/missing coax connections way more than 1/2 the time we're out.

 

[Botch]

Sometimes, the gremlins just appear. Sunday I stopped at the grocery store, turned off the Saab, but the CD player kept playing. I reinserted the key, turned the car on, turned it off, removed the key, still played the dulcet tones of Dream Theater. I let it play, went in the store and got my kumquats, and came back out, still playing. Drove home, got out of the car, and it stopped as usual. Did all day today too. Who knows.

 

[Razz]

wow... strange one here... Sounds to me like me recent DC in my power line. At first I had a lot of confusion over the cable box being an issue. I'm curious how this plays out..

 

[Flint]

for all you know the cable company just installed some new things on the line somewhere in your neighborhood.

 

[Zing]

Check the grounding on the coax cable that serves the house. There cable company's line should meet your wiring at a barrel connector that is grounded at the same point that your homes electrical lines are. Also check that the home's grounding clamp is tight.

My techs work at houses every day and around 20% have loose or improperly terminated grounding clamps. We find coax loose/missing coax connections way more than 1/2 the time we're out.

Would grounding the splitter that feeds my HT cable TV box do any good?

 

[Towen7]

Would grounding the splitter that feeds my HT cable TV box do any good?

I certainly wouldn't do any harm.
Assuming that splitter is outside try this as a temporary measure to see if it's worth doing something permanent; take the longest screwdriver you have and stick it in the ground. Then use any conductor you have laying around and to connect that screwdriver to the body of that splitter.

 

[Flint]

You can buy isolation devices for that purpose, I have inner from Jensen Transformers which works well.

You cannot use isolators on internet feeds, though.

 

[Zing]

The splitter is not outside. It's in the basement. I was thinking I'd ground it to a water pipe ground.

What's outside is the barrel connector you mentioned but that's not grounded. However the cable disappears into a sealed junction box. I don't see an obvious grounding going to the junction box unless it's grounded from behind.

The TV cable cabling system in this house is a nightmare. It looks like the guy who built the house didn't have cable TV but the next owner had it retro-fitted and then the next owner had her 12 year old nephew run lines to every room in the house.

 

[Towen7]

That's worth a shot.

 

[Zing]

Weird. No more hum. It jut went away on its own.

 

[MakeMineVinyl]

Weird. No more hum. It jut went away on its own.

I've found that buzzes and hums do that...then they come back......
I think some of the reason might have to do with EMI on the power line. I have a couple dimmers which will pollute my local power and cause buzzing even rooms far from the source. A power line filter such as from Tripplite is largely ineffective against this type of lower frequency garbage. I've had some limited luck with placing ferrite clamps on the power lines of affected equipment.

Strangely, when I had longer speaker leads going to my main speakers, I would pick up buzzing via the speaker wires with the whole system off! Moving the amps next to the main speakers solved that problem now that the lines are only about 8'.