harmonic distortion in home theater

harmonic distortion in home theater

PostBy: dandy On: Sat Jan 07, 2012 2:35 pm

Guys, a friend I went to visit today has a hum or distortion in his home theater when the main zone circulator starts. The other 2 circulators do not cause any hum. The circulator are grundfos which I am not familular with. I suggested swapping the circulator in question with another one to see if the problem persists. Does anyone have a idea or suggestion how to wnd the hum in the home theater? dan
dandy
 
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Re: harmonic distortion in home theater

PostBy: coaledsweat On: Sat Jan 07, 2012 2:48 pm

Poor ground perhaps? Does the pump run off the same circuit as the TV? Try an extension cord to a different outlet in another area.
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Re: harmonic distortion in home theater

PostBy: rockwood On: Sat Jan 07, 2012 3:28 pm

Could be EMI.
"Broadband interference usually comes from incidental radio frequency emitters. These include electric power transmission lines, electric motors, thermostats, bug zappers, etc"
http://en.wikipedia.org/wiki/Electromag ... terference

You could try to put some kind of metallic shield around the motor and see if stops the interference.
rockwood
 
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Re: harmonic distortion in home theater

PostBy: CapeCoaler On: Sat Jan 07, 2012 11:09 pm

CapeCoaler
 
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Re: harmonic distortion in home theater

PostBy: Yanche On: Sat Jan 07, 2012 11:44 pm

There are two distinctly different kinds of interfering signals, conducted and radiated. Conducted radiation would be interference that gets to the home theater system through the power lines. Is the zone circulator is variable speed circulator? If it is that could be the interference path. As a test try changing the speed of the circulator. If the hum changes you found the source and method of it getting in. Proper grounding and/or a power line filter will correct it.

If the source is radiated, which is doubtful but possible, check the grounding of the circulator circuits particularly the green safety ground. There should be a safety ground path all the way back to the breaker panel. Same for the home theater system components.
Yanche
 
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Re: harmonic distortion in home theater

PostBy: cabinover On: Sun Jan 08, 2012 7:25 am

I have a couple of Bose's monster amps from the late 70's as part of my stereo. We sometimes pull music from Pandora via RCA cables to the preamp. Depending on which amp is serving duty I can get a ground loop hum. The only reason I know this is from chasing it driving me crazy.

I don't know what the difference is between the amps but one needs a cheater plug so as to not use the ground. If I just plug it into the wall for some reason there is a ground loop with the computer. Weird huh?

Maybe your friend has the same thing?
cabinover
 
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Re: harmonic distortion in home theater

PostBy: coalvet On: Sun Jan 08, 2012 9:36 am

I agree with cabinover, I have to use a cheater plug on my powered subwoofer or else the hum would rattle my whole house! Once I put the 3 to 2 adapter on the plug all the hum went away.


Rich
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