Magnetic shielding, what is it worth and why? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 24 Old 08-21-2007, 03:29 PM - Thread Starter
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This may be the boneheaded question of the day but I'm serious (I'm also having troubles with the search feature). But I'm wondering if/when magnetic shielding is something that is worth paying for in a speaker.

I have seen a couple different brands...one currently hot one comes to mind that charges extra for the feature. And I'm wondering why it isn't standard if it is necessary...or if it isn't necessary...what is it's real purpose?

Is it useful when the speaker will be a front or center right by the receiver? Or just near a PC? Or if you have a microwave going off within 6' of it?

Do ya'll pay for shielding? why/why not? This noob mind is wanting to learn.
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post #2 of 24 Old 08-21-2007, 03:38 PM
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Magnetic shielding is more important for CRT's. If you have an unshielded speaker next to a CRT, you'll see all kinds of distorted colors, interference, etc. If you have a DLP, LCD, LCOS or Plasma, they are unaffected by the speaker magnets.

I didn't pay for shielding since I have a LCOS.
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post #3 of 24 Old 08-21-2007, 03:38 PM
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Magnetic shielding is mostly needed if your TV is CRT based (tube), because the magnetic waves from the speaker's driver can affect the picture if placed in close proximity of the TV.....depending on the speaker, around 2 feet or so.

Also, if the speaker will come close to magnetic media, such as a hard drive, magnetic shielding would be a good safe guard.

With CRT based TV/monitors becoming less popular, the need for shielded speakers will go down as well.

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post #4 of 24 Old 08-21-2007, 03:52 PM - Thread Starter
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Ah I was worried about the effect on the sound and not even thinking about the speaker wacking other things...makes much more sense now. I have a Sony RP so I guess I don't have to worry. One more piece in the puzzle. Thanks guys. Now if you can just tell me what speaker pair to buy for under 1K I'll be set...(as if).

Much appreciate the info...will feel less a fool next time
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post #5 of 24 Old 08-21-2007, 03:59 PM
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Remember DVR's have hard drives in them and you don't want unsheilded speakers next to them.

Paradigm charges extra for the Magne-Sheild option and they have great speakers in your price range.

I'm going to put a pair of Atom Monitors on my computer desk and they will be shielded because there are many hard drives close.

I used to have an open mind but my brains kept falling out.
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post #6 of 24 Old 08-21-2007, 04:02 PM
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I wouldn't worry too much about it unless you're using a CRT. I'm running Atoms about 4 inches away from my LCD monitor, and there is no problem (as it should be). Magnetic storage shouldn't be a problem either since there's a huge magnet in hard drives anyways. However, to be safe, I would at least keep it a foot away, at least, from speakers. Even then, I'd be more worried about vibration.
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post #7 of 24 Old 08-21-2007, 04:48 PM
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Quote:
Originally Posted by fanbrain View Post

Remember DVR's have hard drives in them and you don't want unsheilded speakers next to them.

- My HD-Tivo was literally about a foot away from my Paradigm Studio 60's and I didn't have any issues with it during the 3 years I've owned it. My new DirecTV HD-DVR is in the same spot right now. I think you need a bigger magnet directly swiping a HD to have an adverse affect on it.
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post #8 of 24 Old 08-21-2007, 08:15 PM
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Quote:
Originally Posted by critterjr View Post

I have a Sony RP so I guess I don't have to worry.

Huh? That doesn't make sense. RP can be CRT or not CRT.

Ed
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post #9 of 24 Old 08-21-2007, 08:47 PM - Thread Starter
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sorry I have a KDS-55a2020 which is a sxrd ..so I guess I'm safe. Or maybe I've missed something else...always a big possibility in my world.
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post #10 of 24 Old 08-21-2007, 08:57 PM
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Quote:
Originally Posted by critterjr View Post

sorry I have a KDS-55a2020 which is a sxrd ..so I guess I'm safe. Or maybe I've missed something else...always a big possibility in my world.

Yes you're safe with an LCOS TV. No need for magnetic shielding at all.
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post #11 of 24 Old 08-21-2007, 09:09 PM
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What about sound? How does it affect the sound?
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post #12 of 24 Old 08-21-2007, 09:23 PM
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Quote:
Originally Posted by openwheelracing View Post

What about sound? How does it affect the sound?

It shouldn't affect the sound.

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post #13 of 24 Old 03-10-2014, 03:19 AM
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Are you sure? Why don,t afect sound a magnet shield ring on the central pole of my tweeter?
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post #14 of 24 Old 03-10-2014, 04:50 AM
 
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Quote:
Originally Posted by fanbrain View Post

Remember DVR's have hard drives in them and you don't want unshielded speakers next to them.

Why?
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post #15 of 24 Old 03-10-2014, 04:54 AM
 
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Quote:
Originally Posted by corbelli View Post

Are you sure? Why don,t afect sound a magnet shield ring on the central pole of my tweeter?

The magnetic fields in loudspeakers are actually tightly focused around the voice coils. The external magnetic fields of speakers can seem large from the standpoint of sensitive devices such as CRTs, but from the standpoint of actual operation of the speaker, they are tightly focused. CRTs are exceptionally sensitive to external magnetic fields.

That means that it is very hard to add to or subtract significant amounts of magnetism to the voice coils themselves. The means used to reduce external fields vary, but none of them changes the operation of the speaker.
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post #16 of 24 Old 03-10-2014, 04:54 AM
 
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Quote:
Originally Posted by tokerblue View Post

Magnetic shielding is more important for CRT's. If you have an unshielded speaker next to a CRT, you'll see all kinds of distorted colors, interference, etc. If you have a DLP, LCD, LCOS or Plasma, they are unaffected by the speaker magnets.


I didn't pay for shielding since I have a LCOS.

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post #17 of 24 Old 03-10-2014, 06:04 AM
 
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One can safely assume that shielded drivers will soon go the way of the CRT, as their only purpose was to reduce interference with CRTs.
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post #18 of 24 Old 03-10-2014, 06:37 AM
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This thread is from 7 years ago.
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post #19 of 24 Old 03-11-2014, 04:18 AM
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Thanks Arnyk for your response. I have a doubt...

I have a pair of B&W nautilus 801 D( frontal) and HTM 1D ( central speaker). Tweeters are IDENTICAL parts in both except for a magnet shield with o- ring shape centered and added on the bottom plate pole (behind voice coil) of the tweeter in central speaker tweeter that is a shielded speaker).

This magnet ring....don,t affect to magnetic circuit adding o substracting magnetic field and consecuently varing the sensibility or other parameters of the tweeter??

I don,t need shielding in my central speaker. I have a projector. I want the identical or more similar timbrical performance in ALL chanels. Can I to remove this magnet shield without affect the sound or tweeter performance?

Whose is the mecanism of this magnet shielding ring? Reconducting the magnet lines in the bottom tweeter area? Is sure that this don,t modify the intensity of the magnetic field in voice coil?

PD: this tweeter have ferrofluid in the gap magnet circuit.
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post #20 of 24 Old 03-11-2014, 06:47 AM
 
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Originally Posted by corbelli View Post

This magnet ring....don,t affect to magnetic circuit adding o substracting magnetic field and consecuently varing the sensibility or other parameters of the tweeter??
No, because that magnet doesn't surround the voice coil.
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post #21 of 24 Old 10-23-2015, 09:01 PM
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I recently got a used Sony MB150H that's magnetically shielded. I have it sitting a few inches away from an Xbox 360, which does have a hard drive. It just seems the sensible thing to do and I'm surprised fewer speakers are being made without some kind of shielding. Having actually looked up close at the magnets inside small bookshelf speakers- they are substantial to say the least. Not as big as some but I'd be worried about keeping a speaker in close proximity to a hard drive for a length of time. It is true that hard drives have magnets inside of them but they are designed for that purpose and much of the hard drive is shielded from the effects of the magnet. If you were to put a large neodymium magnet on top of a computer it could easily cause the computer's data to be corrupted and unusable in seconds (look it up on youtube, people have tried it in the interests of science).

Last edited by FireDragon76; 10-23-2015 at 09:05 PM.
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post #22 of 24 Old 10-24-2015, 05:57 AM
 
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Quote:
Originally Posted by cschang View Post

Also, if the speaker will come close to magnetic media, such as a hard drive, magnetic shielding would be a good safe guard.
Hard drives aren't affected by permanent magnets. This is a source of confusion, as magnetic fields are used to erase recording tape, but those are alternating magnetic fields.
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post #23 of 24 Old 10-24-2015, 06:59 AM
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Originally Posted by Bill Fitzmaurice View Post
Hard drives aren't affected by permanent magnets. This is a source of confusion, as magnetic fields are used to erase recording tape, but those are alternating magnetic fields.
Are you sure, Bill?

I recall a high school experiment where we put a plane magnet on top of a cassette tape. It didn't erase it, but it did mess up the recording a bit.

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post #24 of 24 Old 10-24-2015, 08:18 AM
 
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Originally Posted by cschang View Post
Are you sure, Bill?
I recall a high school experiment where we put a plane magnet on top of a cassette tape. It didn't erase it, but it did mess up the recording a bit.
If you put it in contact with the cassette it would have some effect, but not much. Tapes are erased using high amplitude high frequency alternating polarity magnetic fields. The frequency of a permanent magnet is 0 Hz. Hard drives contain very powerful neodymium magnets in far closer proximity to the discs than a speaker magnet ever could be.
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