Do speaker magnets affect LCD TVs?

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Do speaker magnets affect LCD TVs?

Postby dh » Fri May 21, 2010 7:34 pm

I want to mount a couple speakers close to the LCD TV, but don't know if they will affect the picture like a tube TV.
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Magnets and lcds

Postby eamarquardt » Fri May 21, 2010 9:49 pm

Magnets can deflect an electron beam in a cathode ray tube. LCD displays work on an entirely different princlple. To generate an electric current in a wire there must be relative motion between the wire and magnet. If your speakers are not moving relative to the screen (and even if they were, I doubt there would be a problem) no unwanted voltage or current will be generated. To test my theory, I just held a reasonably powerful magnet right on the display of my netbook. No effect.

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Postby dh » Fri May 21, 2010 11:03 pm

I didn't think it would, thanks for confirming!
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Postby MceeD » Sat May 22, 2010 1:59 pm

I don't mean to throw gasoline on to a fire. But...

Magnets will have more of an pronounced affect on Tube tv's but they will affect LCD's and Plasma. It is why most home theater and computer speakers are Shielded. If you don't see a visible affect that don't mean it is not affected.

You can find shielded speaker all over the place since so many are made for the above mentioned uses. parts-express sells coaxial speakers and speaker components. That are shielded.
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Postby Larwyn » Sat May 22, 2010 2:47 pm

I think it depends a lot on the accuracy and the force with which you throw them................... :lol: :lol:
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Postby caseydog » Sat May 22, 2010 5:05 pm

Well, I turned to Google, and got answers ranging from "yes, absolutely," to "not a chance."

Yep, the internet is full of information, but it's not all good.

The consensus, if you can call it that, seems to be that magnets won't ruin your LCD monitor, but they can affect the colors temporarily if they get too close.

So, I would just try it and see what happens. But, that's me.

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Bah, humbug!

Postby eamarquardt » Sun May 23, 2010 1:10 am

MceeD wrote:I don't mean to throw gasoline on to a fire. But...

Magnets will have more of an pronounced affect on Tube tv's but they will affect LCD's and Plasma. It is why most home theater and computer speakers are Shielded. If you don't see a visible affect that don't mean it is not affected.

You can find shielded speaker all over the place since so many are made for the above mentioned uses. parts-express sells coaxial speakers and speaker components. That are shielded.


The reason to shield audio cables (IMHO) is to prevent the wires from picking up stray signals that may be reproduced by the speakers. Some speakers, particularly sub woofers, have built in amplifiers that will amplify these stray signals and these unwanted signals will be heard from the speakers. A while back I hooked up a subwoofer with zip cable and got an annoying hum. Switching to coax eliminated the problem.

Here is an article that discusses running an lcd display right next to an MRI machine:

http://www.uncg.edu/~t_hunter/5412419.htm

I can't imagine that if an lcd display can operate in the environment of an MRI machine that a speaker magnet and/or coil would be a problem. LCDs do not (as I understand it) involve magnetic fields to operate unlike crts.

By the way, in case anyone is interested (probably not) but according to my doctor (Dr. Aaron Filler, UCLA) I am the first person in the universe to undergo surgery in real time while in an MRI machine. He used images from the machine to guide him during surgury to clean up the nerves in my neck.

Now, lets "bicker".

Cheers,

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The opinions in this post are my own. My comments are directed to those that might like an alternative approach to those already espoused.There is the right way,the wrong way,the USMC way, your way, my way, and the highway.
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Postby Corwin C » Sun May 23, 2010 9:57 am

Tube screens use a tightly controlled series of magnetic fields to aim an electron stream at phosphors on the screen to create the image. Any magnetic source close to the tube would affect these fields and cause distortion because the path of the electrons would be affected.

LCD screens, on the other hand have a matrix of individual diodes which light up to create the image. They are affected, but are generally shielded to prevent stray signals or loss of signals. Todays electronics use such small current flows and are generally pulsed (digital) such that magnetic fields (especially moving ones) are more probable to cause issues, hence the shielding.

Also, a localized magnetic field (small magnet, small coiled wire (speaker), etc.) is much more likely to cause noticeable distortion than a field that is filling the room (the Earth's magnetic field for example.) I guarantee you that the displays in an MRI room are heavily shielded and are most likely specifically designed specifically for that environment.

Your typical LCD computer screen is shielded enough to handle the speaker systems that are sold in the box stores being placed right next to it without noticeable distortion. I think that unless you are building a highly amplified custom speaker setup, you should have no problems. If you do have issues, shielding can be a simple as lining the inside of the speaker enclosure with grounded foil or even better, products like these.
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What I said

Postby eamarquardt » Sun May 23, 2010 10:24 am

Corwin C wrote:Tube screens .........................................these.


That's what I said, but just not in as much detail.

Cheers,

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The opinions in this post are my own. My comments are directed to those that might like an alternative approach to those already espoused.There is the right way,the wrong way,the USMC way, your way, my way, and the highway.
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Re: What I said

Postby Corwin C » Sun May 23, 2010 4:50 pm

eamarquardt wrote:
Corwin C wrote:Tube screens .........................................these.


That's what I said, but just not in as much detail.

Cheers,

Gus


Can't a guy agree in a disagreeable way ... :shock: :?

eamarquardt wrote:Now, lets "bicker".


After all you're the one who wanted to bicker ... :R :R :lol:
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Re: What I said

Postby eamarquardt » Sun May 23, 2010 11:54 pm

Corwin C wrote:After all you're the one who wanted to bicker ... :R :R :lol:


And you did an excellent job of rising to the occasion. :applause:

Fun bickering with you even though we agree. Even more fun if we disagree. So, which one of us is gonna change our postion. Your serve! :twisted:

Never miss out on a good bicker! :D

Cheers,

Gus
The opinions in this post are my own. My comments are directed to those that might like an alternative approach to those already espoused.There is the right way,the wrong way,the USMC way, your way, my way, and the highway.
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Postby starleen2 » Mon May 24, 2010 8:19 am

And here we go again – sure an LCD within a magnetic field with the strength of Black Hole (if there is such a thing) will be distorted – come on folks. Shielded vs unshielded, Tubes, electrostatic quarto eighth dimension (OK, I made that one up). I’ve seen a lot of teardrops and none come close to the scenarios mentioned. I think that an LCD operating in the close proximity of an MRI machine is good enough evidence for me. Heck, I’m holding a magnet up to my screen right now and NO distortion. My concern would only be is to how to keep the darn thing from falling off the wall while traveling - Geezz
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Postby dh » Mon May 24, 2010 8:44 pm

starleen2 wrote: My concern would only be is to how to keep the darn thing from falling off the wall while traveling - Geezz


Bubblegum :lol: :lol: :lol:

Sorry, I just couldn't leave that one alone.
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