How to shield speakers

Step 1
First, of all, you’ll need to figure out how to get the speaker drivers out of your actual speakers without causing any damage. All speakers are slightly different, so make sure you know how yours are built before you start opening them up with a screwdriver.

Step 2
You will need some kind of metal covering to wrap around the magnetic portion of your speaker drivers. This will capture the magnetic field and keep it from damaging or disrupting your other electronics. Typically, the best option will be something made out of steel that can fit over the circular back of your speaker driver. Measure your drivers, then head to a home improvement store to look for materials that might work. Bring a magnet along to make sure the metal materials you buy are magnetic.

Step 3
Remove the drivers from your speakers and place the steel material on and around the magnet on the back of the driver. Since drivers are circular, so are the magnets you need to cover up. Therefore, if you can find some kind of circular metal cap that is magnetic, that would be your best bet. Make sure the metal covers the magnet entirely, then tape it into place using electrical tape.

Recap
The above steps should shield the magnets in your speakers. Now, when you place the drivers back into your speakers and put the speakers back together, you should no longer have to deal with magnetic fields that could damage or disrupt your other electronics!

My girlfriend needs to use an EEG for a study. They will put the people inside a Faraday cage, to minimize any external interference. It's a small metal room. They need to put speakers inside that metal room and have to shield those wires as well to reduce the interference as much as possible.

How would they go doing that? Would wrapping aluminium foil over the cables, then grounding the foil to the cage be ok?

I suggest you consider that you are asking to solve the wrong problem. You need to get sound to them, it doesn't have to be a speaker. The typical approach for fMRI studies where audio must be piped to the patient is to use a intra-aural sound pipe (usually plastic tube).

I think you would be looking for something like a "pneumatic headphone" or similar.

Thanks! It's an interesting alternative, although we're trying to make do with what we have available. I can't find any for sale online in our country and this has to be done before tuesday. I've suggested the idea for long-term use, though, if they can manage to find out how they work and where to get some.

Fun fact: in MRIs they use these headphones that actually work directly from compressed air. No wires. Maybe you could do somethiing like that?

Edit: now that I'm not on mobile, here is some more info:

It might be a bit overkill for your use though. Speaker wire isn't terribly difficult (it's not very high frequency, etc), so you should be able to use any decent quality shielded wire. Just make sure you ground the wire shielding to the faraday cage (I think). Then, stick the speakers themselves inside mini-faraday cages. I'm just a lowly mechanical engineer (with some experience in MRI compatible devices) but that sounds like it should work.

Your NVIDIA device pairs with Bluetooth accessories such as keyboards, speakers, and headphones. You can also pair with other Bluetooth-enabled devices. Bluetooth functionality is a standard Android feature.

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  1. Follow the instructions from your accessory’s manufacturer to put the accessory into Pair mode.
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  1. Open Settings .
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  3. In the list of Paired Devices , tap the accessory’s Settings icon . The accessory control panel opens.
  4. Tap the Name field .
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Only if you still game on an old CRT and use floppy disks.

How to shield speakers

I’m a huge fan of headphones, as some of you might know. However, nothing can beat the visceral experience of having a good set of powerful speakers. Most people choose to go with PC speakers, but for those who want a bit more fidelity and punch, home-theater bookshelf speakers are the way to go.

There’s only one issue: almost all home-theater speakers are unshielded. But is this really a problem?

It’s generally known that speakers, especially large ones, have huge magnets inside of them that drive the movement of a speaker’s cones. And it’s generally believed that having powerful magnets next to computer gear can be a recipe for disaster.

However, unshielded speakers were more of an issue back in the days when everyone was using a CRT monitor—you know, those huge displays that you don’t really see anymore. CRT monitors were easily affected by magnets, even small ones, which when placed in close proximity to the display would cause color and image distortion. LCDs however, are immune to such effects. In this case, you don’t have to worry about what type of speakers you place next to your display.

But what about your PC? Aren’t hard drives affected by magnets?

Actually, yes and no. Despite what the general public believes, hard drives are fairly resistant to magnetic fields from common magnets. In fact, hard drives have two very powerful rare earth magnets inside of them that are crucial to controlling their read/write actuators. If you’ve ever taken a hard drive apart, you’ll know that the two magnets inside are dangerously powerful. The actuator magnets actually sit right next to the platters. It is highly unlikely that placing your PC next to a home-theater speaker will impact it in any negative fashion.

So you’re telling me that I can’t erase a hard drive with some powerful neodymium magnets?

No. In fact, you can stick two powerful magnets on either side of a hard drive, turn the drive on, and operate normally without errors. This has to do with the coercivity of the materials used for a hard drive’s platters, which is the measure of the material’s resistance to changes in magnetization. Platters have very high coercivity and require exceptionally strong electromagnetic fields to change. If you want to scramble the data on a hard drive, you’re better off taking a hammer to the thing instead of using magnets.

We no longer live in a world of fat CRTs and floppy disks. So go ahead, grab some monster sounding speakers and use them for gaming, music, and movies. They’ll sound better than any PC speakers you can buy.

I just generally keep my speakers at a distance so it doesn't impact any monitors. No reason they need to be up right against them really.

Yeah generally I space them out too, but I wanted to know if there was any other way than moving the speaker closer to see if the CRT changes color lol.

If they say "Magnetically Shielded Type" 😛

Most speakers aren't, unless they say they are.

Yes, but I’m saying that’s the only time I have seen speakers labeled as such. I have had some speakers that were but don’t say it, but the app is something I never thought of.

You can usually get apps for your phone that can read the magnetic sensor. Bring your phone near the speaker. (Not a joke)

Like another comment said, if it says it's magnetically shieled, you can be safe knowing it actually is. If it doesn't say, you can try opening it up (remove the woofer), and see if in the back of the speaker driver you see either the (usually) black ferrite ring magnet (not shielded), or a metal "cup" over it (shielded). If you're still unsure, try using something like a screw or nail just to check it. Make sure it's ferromagnetic, though, as in, it sticks to an actual regular magnet.

Another method, as someone else suggested, is to use a magnetic sensor app, as most phones have one.

with most speakers a small amount of water shouldn’t be a big deal. i’m sure my lats set of mids and my current mids have seen at least a small amount of water.

i’d say as long as the voice coil isn’t open in any way and the cone isn’t paper then you should be fine.

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Hertz Mille. For the cost of these I would prefer to keep them dry //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Brian_smith06

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FoxPro5

Causal wanderer

Make a rain guard out of tin foil and plumbers backstrap.

You can use the foam baffles, but you need to cut the bottom out of them. If you’re doing this, I hardly see how they are worth the cost.

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The most expensive solution is the one that doesn’t do the job correctly.

AndyInOC

Senior VIP Member

I saw on another forum that a guy used some aluminum sheet to shield his. Basically he cut a wide strip to cover past the magnet, bent one edge up and cut notches in it, then bent the entire piece to a semi-circle to conform to the shape of the speaker. He screwed the metal between the speaker baffle and the door and the whole assembly was deadened. Hope my terrible description helps lol

Heres the link, this guy shows and describes it WAY better since its his idea lol

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buggsson

Senior VIP Member

I would build a glass fiber box for them, or are they built to play in the whole door?

DidUHearThat?

Precious Bodily Fluids

You should replace the window seals. Then you just need some way of blocking the water from dripping onto the top of the drivers. Like an extra flap of deadener ever the top/back of the driver, to allow water to run off. I wouldn’t seal up the back of the driver though. You could create a moisture build up that can’t dry out and ruin the driver faster than with no cover. Also it would ruin your bass response.

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tcguy85

CarAudio.com Veteran

how about some of the thin gladware / tuperware containers chopped in half? that would be a good cheap rain guard.

07 Scion tC: 880PRS, ID OEM 6.5" mids, Seas neo alum tweets, DD S4 and DD C2a amps, Dayton Ref H.O. 10(.7net, tuned to 30hz)

HT: Samsung PN58B560 – 80gig PS3 – Yamaha RX-V2500 – Infinity Alpha 50 mains – Alpha center – Harmon Kardon HKB6 rears, Epik Sentinel & ED eQ.2.

lyttleviet

CarAudio.com Elite

Use foam baffles you can buy from crutchfield and cut the *** end out. Cheapest and most effective way I have found as of yet.

Buyer/Seller Feedback thread:

bikinpunk

G-g-g-g-g-unity!

I saw on another forum that a guy used some aluminum sheet to shield his. Basically he cut a wide strip to cover past the magnet, bent one edge up and cut notches in it, then bent the entire piece to a semi-circle to conform to the shape of the speaker. He screwed the metal between the speaker baffle and the door and the whole assembly was deadened. Hope my terrible description helps lol
Heres the link, this guy shows and describes it WAY better since its his idea lol

i read through that. To be honest, I’d rather buy the foam guards. You pay about $15-20 shipped. His thread says "under $25". The foam gurads are and it’s less work.

Sheilded drivers are designed that way. You can't "add shielding" to a
driver.

Yes, it's possible to use a bucking magnet to produce a field that counters
out the field of the woofer magnet, but it's difficult to make it work
right in all directions unless the woofer is designed for it.

Yes, it's possible to use mu-metal or very thick ferrous alloys to shield
the thing, but half-inch steel plate also doesn't help the room acoustics.

What you want to do is more difficult than trading the speakers in for
some that are designed for low leakage.
–scott

"C'est un Nagra. C'est suisse, et tres, tres precis."

Mike Rivers

> I have searched all over the web and I can not find any info on how to
> magnetically shield a speaker. I got a nice pair of Tannoy System 800
> monitors for a geat price and I need to get some shielding for 1 of them
> because it is to close to my PC monitor and I can not move the PC
> monitor

What's all this "I can't" that I'm reading here these days? Can't
move the monitor, can't re-record the part, can't afford what you
really think you need . . . Move something, dammit. You will never
successfully shield the speaker. Move into another room. Move into
another house or shop. Move the monitor out to the kids' room and
move in one that's better shielded.

Speakers that are designed to operate near CRTs aren't just shielded,
they have magnets specifically designed to have closely contained
fields.

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Shielding Materials

What material is best for shielding a magnet? How can I block a magnetic field?

Have you ever wondered about how to shield a magnet? Can a magnetic field be blocked so a magnet only pulls on one side? Need to shield a sensitive device from magnetic fields?

What is a Magnetic Shield?

How to shield speakers

First, one important point must be clear: Magnetic shielding does not block a magnetic field. No material can stop the lines of flux from traveling from a magnet's orth pole to it's south pole. The field can, however, be redirected.

In the series of pictures below, follow the lines of flux as paths from one pole of the magnet to the other. In the first, a magnet in free space is shown, with the field lines flowing through air. In the second, a wall of steel provides an "easier" path for the lines of flux to follow. These lines flow out from the magnet's pole, into the steel for some distance, and back out into the air to get back to the magnet's other pole. In the third picture, a steel enclosure reduces the ambient field strength inside by providing a path around either side of the space.

What material will work?

The short answer is: Any ferromagnetic metal. That is, anything containing iron, nickel or cobalt. Most steels are ferromagnetic metals, and work well for a redirecting shield. Steel is commonly used because it's inexpensive and widely available. Note that some stainless steels, especially the 300 series varieties, are not ferromagnetic.

How thick should my shield be?

This will depend on many factors. What is the size and nature of the magnetic field you're shielding? What are you shielding it from? Does it make sense to shield the magnet, or your magnetically sensitive device? Is your shield a perfect sphere, a closed cylinder, or some other shape?

The thickness of the shield matters, up to a point. When the shield is too thin, it becomes saturated, and can't "hold" any more lines of flux. You want it to be thick enough to hold as much flux as possible. However, once you reach a certain limit, adding steel thickness won't improve your shielding much.

In some cases where saturation is an issue, multiple layers of material are used.

See the animation at right, where the thickness of a steel wall is varied. Once it gets below a critical thickness, the material is saturated. It can't hold any more lines of flux. At that point, the flux pops out the far side, and travels through the air.

But what about other metals? Don't I need some fancier shielding material?

Yes, there are some specialized materials specifically made for magnetic shielding. The foremost of these is MuMetal, an industry reference material defined in Milspec 14411C. Companies that provide magnetic shielding materials typically offer a version of MuMetal, and some other proprietary alloys. Most of these have a high nickel content, with either 50% or 80% nickel in the mix.

Specialized magnetic shielding materials usually have a higher relative permeability, but a lower saturation point.

Permeability is the degree of magnetization of a material that responds linearly to an applied magnetic field. For shielding, Relative Permeability is the Permeability divided by the Permeability of free space, a constant. In more practical terms, Permeability is a measure of a material's ability to absorb magnetic flux. The higher the number, the better the shield.

Low carbon steels have a Permeability of 1000 – 3000, while MuMetal can have values as high as 300,000 – 400,000.

The saturation point is the flux density at which the material can not contain any more magnetic flux. Steel saturates around 22,000 Gauss, while MuMetal saturates at about 8,000 Gauss.

In lower flux density fields, such high permeability materials provide greater attenuation. In higher field densities, MuMetal becomes saturated, and loses its effectiveness. In these cases, steel provides good attenuation and a much higher saturation threshold.

Conclusion

Which material is right for you depends on your specific shielding problem. For low field strength, sensitive electronics, MuMetal can provide better shielding than steel. For many applications involving large, powerful neodymium magnets, the higher saturation point of steel serves better. In many specific cases we're asked about, a steel sheet-metal shield is often the best solution.