BUZZ sound from tv speakers!! HELP - AVS Forum
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post #1 of 19 Old 03-22-2012, 09:35 PM - Thread Starter
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Hello. Bit of a long story but please help me. I have recently finished my basement and used a (very thin and cheap) RCA cable to connect a tv in a seperate room of my house from a dual tuner PVR satellite receiver. problem is now that basement is done I am unable to replace my poor quality cable. Now my tv connected to the RCA gives off a very loud buzz noise from my speakers. When I unplug the L/R audio and leave the video connected the buzz stops. When I plug back in... I almost go crazy from this buzz! I have been researching and I think this my help. I also read about "RCA attenuator" to reduce signal due to "over modulation" This is getting complicated to me. But I also saw rca isolator ground loop. also titiled a noise eliminator. What do I need??? please help. Thank you

Darryl
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post #2 of 19 Old 03-23-2012, 04:55 AM
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Originally Posted by blazzer_19 View Post

Hello. Bit of a long story but please help me. I have recently finished my basement and used a (very thin and cheap) RCA cable to connect a tv in a seperate room of my house from a dual tuner PVR satellite receiver.

The problem is probably not the wire you used provided that it is shielded and doesn't have any dry wall screws or nails driven through it.

The problem is most likely that you connected a device that is hooked to an outside antenna to an audio amplifier (or receiver).

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problem is now that basement is done I am unable to replace my poor quality cable.

First question - did you ever try this hookup (satellite receiver to audio amp) before?

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Now my tv connected to the RCA gives off a very loud buzz noise from my speakers. When I unplug the L/R audio and leave the video connected the buzz stops. When I plug back in... I almost go crazy from this buzz! I have been researching and I think this my help. I also read about "RCA attenuator" to reduce signal due to "over modulation" This is getting complicated to me. But I also saw rca isolator ground loop. also titiled a noise eliminator. What do I need??? please help. Thank you

I would spend my money on the ground isolator. They are so useful that I keep one handy at all times. You probably have what is known in the trade as a ground loop.
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post #3 of 19 Old 03-23-2012, 05:24 AM - Thread Starter
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oh thank you sooo much for your help. I was careful when I strung my cable and tried my best to keep it from areas where screws could hit it. Anything can happen and I am not a pro but I believe that is unlikely in this case. This particular setup is connecting my satellite receiver to my bedroom tv via composite/RCA cable. I am not using an amp for this setup. I did try the setup with a dvd player and it seemed fine... but the satellite is terrible. I notice it particularly in sports news shows. with the fancy deep colour graphics .... red and white colours seem to increase the buzz / humming sound. When I watch a normal show or movie the buzz is significantly reduced. I know it sounds weird but colour affects it. I have never had this problem. I read about ground loop and these attenuators. supposed to reduce signal strength to reduce noise due to (what i have read to be) "over modulation" I am at a loss. you believe that ground loop is a good place to start?
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post #4 of 19 Old 03-23-2012, 05:43 AM
 
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You are getting the buzzing, because of the cheap RCA cables which have no real shielding. It has nothing to do with a ground loop hum or a OTA antenna. Now of course, your only choice will be cutting into the drywall to pull out the bad cables, and run the new better quality.
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post #5 of 19 Old 03-23-2012, 05:44 AM
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Originally Posted by blazzer_19 View Post

oh thank you sooo much for your help. I was careful when I strung my cable and tried my best to keep it from areas where screws could hit it. Anything can happen and I am not a pro but I believe that is unlikely in this case. This particular setup is connecting my satellite receiver to my bedroom tv via composite/RCA cable. I am not using an amp for this setup. I did try the setup with a dvd player and it seemed fine... but the satellite is terrible. I notice it particularly in sports news shows. with the fancy deep colour graphics .... red and white colours seem to increase the buzz / humming sound. When I watch a normal show or movie the buzz is significantly reduced. I know it sounds weird but colour affects it. I have never had this problem. I read about ground loop and these attenuators. supposed to reduce signal strength to reduce noise due to (what i have read to be) "over modulation" I am at a loss. you believe that ground loop is a good place to start?

Yes, I think that a ground loop Isolator is a good place to start. If you have grounding problems the video can contaminate the audio, which is what you seem to be experiencing.
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post #6 of 19 Old 03-23-2012, 05:57 AM
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You are getting the buzzing, because of the cheap RCA cables which have no real shielding.

No, not at all.

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It has nothing to do with a ground loop

It has nothing to do with shielding.
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post #7 of 19 Old 03-23-2012, 06:03 AM - Thread Starter
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so how does shielding work then?? Why do different colours affect buzz differently?? and next.... why was there no buzz at all when I connect the cable with dvd player? There was no buzz with dvd so why with satellite? I feel there has to be a reason and a way to improve as opposed to ripping out drywall. Arnyk comes across as having a better more technical understanding.
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post #8 of 19 Old 03-23-2012, 06:06 AM - Thread Starter
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thank you sam64 also
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post #9 of 19 Old 03-23-2012, 06:40 AM
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Why do different colours affect buzz differently??

Missed that...that's most likely due to failing components in the demodulator section of your receiver.
It can happen at the transmission side as well, but isn't likely.

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why was there no buzz at all when I connect the cable with dvd player?

DVD players don't involve a transmitter or receiver.

Try a new/different receiver.
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post #10 of 19 Old 03-23-2012, 08:13 AM
 
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Originally Posted by blazzer_19 View Post

so how does shielding work then?? Why do different colours affect buzz differently?? and next.... why was there no buzz at all when I connect the cable with dvd player? There was no buzz with dvd so why with satellite? I feel there has to be a reason and a way to improve as opposed to ripping out drywall. Arnyk comes across as having a better more technical understanding.

Cheap cables have no shielding. Everyone on these boards are apt to jump out and tell people to go out and get some magic device/snake oil thinking that it will fix the problem, when it really doesn't.
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post #11 of 19 Old 03-23-2012, 08:18 AM
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Everyone on these boards are apt to jump out and tell people to go out and get some magic device/snake oil thinking that it will fix the problem, when it really doesn't.

...and others will tell you it's due to an 'impedance mismatch' or 'cheap cables', when that has no basis in reality. They'll never explain themselves either, because they really don't know what 'impedance' or 'electrostatic shielding' means.
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post #12 of 19 Old 03-23-2012, 04:43 PM - Thread Starter
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I feel more confused. Anyway I have contacted sellers of ground loop isolators. they are saying most often these are used in car audio applications. they say they dont know if this will fix my problem. But I am gunna try it cause its my only option. I am hoping that the "shielding" is fixed by running through this Isolator. This cable both is connected from Satellite direct to my tv. So I will connect it from satellite to isolator then to tv and hopefully this works.
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post #13 of 19 Old 03-23-2012, 06:29 PM
 
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It will not fix the
damaged or poor shield on the cables. Only way, is to replace with good quality cables.
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post #14 of 19 Old 03-24-2012, 07:16 AM
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It will not fix the
damaged or poor shield on the cables

How do you know there's a damaged shield?
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post #15 of 19 Old 03-24-2012, 09:00 AM
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You didn't happen to run your wires near a fluorescent light or dimmer switch?
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post #16 of 19 Old 03-28-2012, 08:51 PM - Thread Starter
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no to the lights but in fact about 3 feet from a dimmer switch. I did some testing. whether the switch is on or off, high or low... doesnt make a difference in the sound.
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post #17 of 19 Old 03-29-2012, 06:56 AM
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I notice it particularly in sports news shows. with the fancy deep colour graphics .... red and white colours seem to increase the buzz / humming sound.

As mentioned, this is a fault with the demodulator, or the modulator if you're using a ch3/4 output.
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post #18 of 19 Old 04-04-2012, 07:47 PM - Thread Starter
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Ok just for an update!! with good news... First I am going to start by thanking arnyk and sam64 for your help. I spent $12 on ebay and bought a ground loop isolator and bam!!!! BUZZZZZZZ gone!!!!!!!!! clear as a bell! Gregzol though sounding confident... wrong! very simple rca audio isolator for 12 bucks!!!! SOOOOO HAPPY
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post #19 of 19 Old 04-05-2012, 12:18 PM
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Quote:
Originally Posted by blazzer_19 View Post

so how does shielding work then??

One of the more surprising factoids is that at audio frequencies and line levels, shielding often does not do a heck of a lot. It is primarily an advantage at high frequencies (e.g. above the audio band), with high impedance circuits (generally not used in audio) and/or very low level signals (e.g. the output of a microphone or turntable pick-up).

Some high end audiophiles even favor cables with no shielding or the shielding disconnected. Usually, no shielding does not hurt audio.

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Why do different colours affect buzz differently??

You've got some kind of grounding problem that is mixing some tiny bit of the video signal back into the audio. It might have not been the colors as such, but rather the changes in intensity that goes with changes in color, that was causing changes to the video signal that sound differently. The actual color in a regular coax video signal is not a big component of the signal.

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and next.... why was there no buzz at all when I connect the cable with dvd player?

The source of the noise in your audio was a grounding problem. DVD players usually have 2 conductor power plugs and are not grounded to your power wiring.

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There was no buzz with dvd so why with satellite?

Satellite video cable is grounded for safety reasons. Its basically an outdoor antenna and therefore a good ground to deal with lightening and the like are a good idea.

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I feel there has to be a reason and a way to improve as opposed to ripping out drywall. Arnyk comes across as having a better more technical understanding.

Well thanks for the encourgement. I have advanced formal education, I've worked in many different technical areas within electronics for decades, and my experiences are highly varied. I've done electronics for years while wearing both blue and white collars. ;-)

Besides, I've had this very problem and fixed it, and not fixed it in many circumstances. Obviously, when the solution I suggested to you didn't work, the cause was that the problem was something else. Because of my technical training and the test equipment I'm fortunate enough to have, I've looked at many of these problems from a number of different directions.
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