Center Channel Speaker/TV Interferance - AVS Forum
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post #1 of 16 Old 11-11-2009, 05:18 AM - Thread Starter
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Yesterday I replaced some analog connections going in and out of my Denon 890 avr. I replaced an analog video and audio connection from my cable box and replaced them with optic cable and s video cable. I then swapped out analog video for s video from avr to my TV. NOTE: MY TV is not a flat panel.

I placed my center channel speaker, Klipsch WC-24 back on top of the tv and reconnected it. I now have horizontal discoloration all the way across the top of the TV. I'm assuming it's interference because of the speaker-when I lift it up it the discoloration goes away- but what I don't understand is that I've had the speaker sitting on top of the TV for a month and never had the problem.

Any thoughts would be appreciated.
Scott
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post #2 of 16 Old 11-11-2009, 05:38 AM
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Quote:
Originally Posted by seal66 View Post

Yesterday I replaced some analog connections going in and out of my Denon 890 avr. I replaced an analog video and audio connection from my cable box and replaced them with optic cable and s video cable. I then swapped out analog video for s video from avr to my TV. NOTE: MY TV is not a flat panel.

I placed my center channel speaker, Klipsch WC-24 back on top of the tv and reconnected it. I now have horizontal discoloration all the way across the top of the TV. I'm assuming it's interference because of the speaker-when I lift it up it the discoloration goes away- but what I don't understand is that I've had the speaker sitting on top of the TV for a month and never had the problem.

Any thoughts would be appreciated.
Scott

Move the speaker, can't have it there....mount a shelf on the wall and your set. You basically answered your own question....If wall mounting is out of the question, I'm sure you could find something to enhance the magnetic shielding of the speaker. AS for the S-Video, I would recommend component over the s-vid if possible, s-vid is the lowest of the low!!! It's time to pick up a flat panel my friend!! You should find some great deals here over the next coule of months...cheap, cheap, cheap!!!!
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post #3 of 16 Old 11-11-2009, 05:45 AM
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Speaker coils generate strong magnetic fields. Those fields bend the electron beams used to draw the picture on the faceplate of a CRT TV. In some cases, they can also magnetize the supports in the TV, causing permanent problems. Some speakers are designed to be used near TVs. They include magnetic shielding called MuMetal and can be quite a bit more expensive than unshielded speakers.

These problems don't exist for flat-panel TVs.

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post #4 of 16 Old 11-11-2009, 08:46 AM
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I would suggest simply returning to the original cable configuration in the following steps, continuing to the last step if there is no change:

(1) Replace the optical cable with an analog video cable into the COAX audio input.
(2) Replace the S-video cable with an analog video cable.
(3) Replace the analog video cable (plugged into COAX input) with analog audio cables and wait until you upgrade to an HDTV.

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post #5 of 16 Old 11-11-2009, 10:05 AM
 
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s-vid is the lowest of the low!!!

No, RF is, followed by composite...which is what he switched from.

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Speaker coils generate strong magnetic fields.

Fortunately those fields are confined to the gap between the poles of the huge permanent magnet found in every speaker. The permanent magnet is affecting the colour purity of the CRT. Move the speaker.

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They include magnetic shielding called MuMetal and can be quite a bit more expensive than unshielded speakers.

They generally use a bucking magnet which is a hell of a lot cheaper then mumetal.

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I would suggest simply returning to the original cable configuration in the following steps,

Why?
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post #6 of 16 Old 11-11-2009, 10:16 AM
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Quote:
Originally Posted by seal66 View Post

Yesterday I replaced some analog connections going in and out of my Denon 890 avr. I replaced an analog video and audio connection from my cable box and replaced them with optic cable and s video cable. I then swapped out analog video for s video from avr to my TV. NOTE: MY TV is not a flat panel.

I placed my center channel speaker, Klipsch WC-24 back on top of the tv and reconnected it. I now have horizontal discoloration all the way across the top of the TV. I'm assuming it's interference because of the speaker-when I lift it up it the discoloration goes away- but what I don't understand is that I've had the speaker sitting on top of the TV for a month and never had the problem.

Any thoughts would be appreciated.
Scott

This will likely not fix your problem but I had a similar issue a while back. TV image was fine but then I temporarily moved my magnetically shielded center speaker to redo some AV connections, put the speaker back where it was on the tv, then all of a sudden, the image was distorted even though it wasn't before. What I found was that I had to turn the tv off for about 10 minutes, then place the speaker on top of the tv, wait about another 5 minutes, then turn the tv back on. After I did that, no more distortion. It didn't make much sense to me and it probably won't fix your issue, but could be worth a try.
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post #7 of 16 Old 11-11-2009, 10:20 AM
 
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It didn't make much sense to me and it probably won't fix your issue, but could be worth a try.

You degaussed the TV, compensating for the external magnetic field.
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post #8 of 16 Old 11-11-2009, 10:35 AM
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Thanks for mentioning that RF is the worst. I always group composite together in my head, forgetting about RF. I don't miss the days of feeding composite into the modulator into the TV. It's interesting to remember how it was with computers and video games years ago.

I just hooked up an SNES with an S-Video cable, and it looks pretty good converted to HDMI! The colors look good, and the image is stable. It's only a small improvement over the composite output I think, though. I was never impressed with S-Video's upgrade over composite though. I mainly noticed the difference with lettering on the screen.

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post #9 of 16 Old 11-11-2009, 12:27 PM - Thread Starter
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Quote:
Originally Posted by marty1781 View Post

this will likely not fix your problem but i had a similar issue a while back. Tv image was fine but then i temporarily moved my magnetically shielded center speaker to redo some av connections, put the speaker back where it was on the tv, then all of a sudden, the image was distorted even though it wasn't before. What i found was that i had to turn the tv off for about 10 minutes, then place the speaker on top of the tv, wait about another 5 minutes, then turn the tv back on. After i did that, no more distortion. It didn't make much sense to me and it probably won't fix your issue, but could be worth a try.


THANKS marty1781! THAT DID IT.
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post #10 of 16 Old 11-11-2009, 12:36 PM
 
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I was never impressed with S-Video's upgrade over composite though.

It's not really an upgrade, it's still NTSC, it's just seperate chroma and luma.
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post #11 of 16 Old 11-11-2009, 12:58 PM
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Originally Posted by seal66 View Post

THANKS marty1781! THAT DID IT.

Although this may have fixed your problem for now, what you have demonstrated is that your Center speaker is producing an unshielded magnetic field which is having a bad effect on your TV.

Such TVs can only handle so much of that before you will permanently damage the TV -- magnetizing some portions of it near the speaker that will eventually not fully recover by the de-magnetizing the TV does each time you power it on.

Unless you don't like that TV very much, and intend to replace it, you would be wise to move that Center speaker further away from that TV. Note that digital TVs (plasma, LCD, DLP) are not subject to this problem.
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post #12 of 16 Old 11-11-2009, 09:36 PM
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Originally Posted by Bob Pariseau View Post

Although this may have fixed your problem for now, what you have demonstrated is that your Center speaker is producing an unshielded magnetic field which is having a bad effect on your TV.

Such TVs can only handle so much of that before you will permanently damage the TV -- magnetizing some portions of it near the speaker that will eventually not fully recover by the de-magnetizing the TV does each time you power it on.

Unless you don't like that TV very much, and intend to replace it, you would be wise to move that Center speaker further away from that TV. Note that digital TVs (plasma, LCD, DLP) are not subject to this problem.
--Bob

I don't doubt what you are saying. In my experience though, I left the center speak on top of the tv (34" Sony tube HDTV) for over 5 years and just recently sold the tv. There were no issues with the tv when the center speaker was removed, everything on the tv was just fine, no distortions. I guess I just got lucky.
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post #13 of 16 Old 03-13-2010, 09:36 AM
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Originally Posted by Marty1781 View Post

I don't doubt what you are saying. In my experience though, I left the center speak on top of the tv (34" Sony tube HDTV) for over 5 years and just recently sold the tv. There were no issues with the tv when the center speaker was removed, everything on the tv was just fine, no distortions. I guess I just got lucky.

Older Sony tube sets have a lot better internal shielding then many other CRT's seem to. I had an older 92 Sony set and it was unaffected as well, just like your TV, in fact I still have it and had a center on top for like 8 years no prob whatsoever, the same does not hold true with many other brands.

A look inside these better sets shows that there are actual shields inside the sets this did help with stray fields quite a bit, the newer ones had it removed to save money, my buddy was a TV Tech so I know this to be true.

Did he also have a Sony I may have missed that in his post?

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post #14 of 16 Old 03-13-2010, 10:21 AM
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A decade or so ago, I owned a 15" NEC (CRT) monitor, for which the setup instructions recommended aligning the display facing [Magnetic] East, in some kind of 'technophilic' Feng Shui! I had recently worked at a Japanese corporation where all the desks on the office floor were lined up in rows facing one direction, and I had visions of CRTs all bolted to desks at the same angle to minimize interaction with Earth's magnetic field...?!

Fortunately, I never placed any speaker near the monitor so I was saved whatever Karmic punishment would have resulted from doing so!

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post #15 of 16 Old 03-13-2010, 10:44 AM
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Originally Posted by SoundChex View Post

A decade or so ago, I owned a 15" NEC (CRT) monitor, for which the setup instructions recommended aligning the display facing [Magnetic] East, in some kind of 'technophilic' Feng Shui! I had recently worked at a Japanese corporation where all the desks on the office floor were lined up in rows facing one direction, and I had visions of CRTs all bolted to desks at the same angle to minimize interaction with Earth's magnetic field...?!

Fortunately, I never placed any speaker near the monitor so I was saved whatever Karmic punishment would have resulted from doing so!

Great Post, unfortunately in some cases this may lead to watching tv from your, Kitchen if this just happens to be the correct Karmic position of where you should have your TV and speakers. Try explaining that one to your guests. :-)

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post #16 of 16 Old 03-13-2010, 08:12 PM
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Originally Posted by SoundChex View Post

A decade or so ago, I owned a 15" NEC (CRT) monitor, for which the setup instructions recommended aligning the display facing [Magnetic] East, in some kind of 'technophilic' Feng Shui! I had recently worked at a Japanese corporation where all the desks on the office floor were lined up in rows facing one direction, and I had visions of CRTs all bolted to desks at the same angle to minimize interaction with Earth's magnetic field...?!

If you aligned them all facing west and turned them on at the same time, the resulting drag on the earth's magnetic field would have slowed the planet's rotation!
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