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Discussion Starter #1
Planning on doing an isobaric horn enclosure for two old KEF drivers, B139s, and am wondering if I mount them magnet to magnet (trying to cancel mag field as running under my CRT TV and these guys screw the sreen from 3ft away) will sound/output suffer at all?

Thoughts please:)
 

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Putting two magnets too near isn’t a good idea, they will cancel each other plus they are demagnetizing since time.
Installing them at distance, let say bigger than one-two magnet’s diameters is acceptable. The farer the better, magnetic force is reversely proportional to the square of distance.
Monitors are very sensitive to the magnetic field. There are used special demagnetizing coils because of even the earth magnetic field affects on the CRT.
 

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Discussion Starter #3
Damnit-this is what I feared.

I know how susceptable CRT's are to magnetic waves-used to get a CCTV monitor to pulse with my bass line from 30ft away:) But that's before i went all SQ...
 

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I hardly imagine why you want them placed by magnet-to-magnet. Usually it’s easier to join them by faces. Plus, the chamber between speakers has to be minimal because of the air inside has a weight too.
 

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Putting two magnets too near isn’t a good idea, they will cancel each other plus they are demagnetizing since time.
Installing them at distance, let say bigger than one-two magnet’s diameters is acceptable. The farer the better, magnetic force is reversely proportional to the square of distance.

Monitors are very sensitive to the magnetic field. There are used special demagnetizing coils because of even the earth magnetic field affects on the CRT.

The black smells like BS, they are permanent magnets and require a HUGE field to charge them initially...

The relative minor field they produce on there OWN isn't nearly enough to change characteristics of either of the speakers magnets..

I call BS on that...


AFA what's in blue, perfectly acceptable and normal, I doubt the earth's field is an issue, but it's true that many CRT monitors have/had (do people use CRT's anymore? lol) degaussing rings built in, because it was so easy to have stray field from just bout any speaker to cause problems...
 

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By connecting two magnets by same poles you neutralize their field.
Magnets are manufactured by magnetizing them by very strong magnetic field and there is a reversed effect too.
Degause coils appeared because of the earth magnetic field magnetizes the shadow mask of the color CRT.
I don’t see a BS there.
 

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Discussion Starter #7
I hardly imagine why you want them placed by magnet-to-magnet. Usually it’s easier to join them by faces. Plus, the chamber between speakers has to be minimal because of the air inside has a weight too.
I already stated why I want them magnet to magnet-I need the magnets to not interfere with my old CRT screen. I know that speakers shipped via air have to be mounted like this to prevent them interfering with the plane's instruments so presume that their mounting cancels the external magnet fields. I'm well aware the traditional clamshell is the easiest to build, but don't want to waste my time if it's going to kill the TV.

Aaron, the plasma is in the bedroom, CRT is in a bay window on the front of the house and replacing it with a plasma would be an open invite to theives-besides CRT still gives a better picture...

So, we have only two opinions-anyone else going to chime in?
 

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Something happened with my attention, it's kinda I’m becoming old. So you want to kill the field intentionally.
If you put them face to face the far fields will be canceled too. Also you can try to use a shield made in sheet of metal to short those fields. Though i hadn't tried it but TV receivers work many years with shielded speakers.
 

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Discussion Starter #9
They were shipped face to face (cable tied together) and they defo screw the TV as is:(

Looks like I'll have to do a trial and if that doesn't work the floorboards will be coming up and the box will go under the sofa:

+more space in lounge
- missus won't like the idea of me ripping up the floor for audio
 

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I don't get it. Why not just shield them off? Shielded speakers are nothing more than a metal cap over the magnets that prevents the magnetic field from escaping. Doesn't sound all that difficult. You could probably even salvage some caps from some old speakers and glue those on.
 

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By connecting two magnets by same poles you neutralize their field.
Magnets are manufactured by magnetizing them by very strong magnetic field and there is a reversed effect too.
Degause coils appeared because of the earth magnetic field magnetizes the shadow mask of the color CRT.
I don’t see a BS there.
You aren't connecting 2 magnets to the same poles though, they would be separate "possibly" overlapping fields.. They might be on the same plane, but they aren't sharing the same pole...

I mean if what you where saying was true, any sub with a stacked magnet structure wouldn't be able to hold a magnetic charge for anything because in the close proximity stacked magnets are IN, they WOULD be sharing a pole

You'd have 2 doughnut shaped fields sitting on top of one another...

You should know the field is both shielded and focused by the top/bottom plates.. and have that doughnut shaped field..

So I still don't understand how they would kill the charge..
 

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There exist exotic variants with dual gaps or multi-pole or curved flux magnets.
Mainly the stacked magnets are aligned in series. They don’t distort their fluxes and just use neighboring magnet to conduct its own flux. Gap between them creates a “broken magnetic flux”. This flux is weak and just helps to main gap to compensate stiffness of suspension. The rear plate it’s a magnetic conductor to redirect the flux toward the gap ,it can be considered as a shield but quite inefficient. I’m agreed, maybe I was too hasty with demagnetization.

Worth a try, though my metal works skills and tools are somewhat limited-is it just sheet steel/iron that will work or anything else?
It’s like those magnets are too strong to be shielded.
I just tried it with one magnet from 10`` subwoofer. 2 millimeters steel sheet works, but not as good as I expected. You can try to arrange them magnet to magnet, but at very close distance the motor strength will be significantly decreased.
 

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There exist exotic variants with dual gaps or multi-pole or curved flux magnets.
Mainly the stacked magnets are aligned in series. They don’t distort their fluxes and just use neighboring magnet to conduct its own flux. Gap between them creates a “broken magnetic flux”. This flux is weak and just helps to main gap to compensate stiffness of suspension. The rear plate it’s a magnetic conductor to redirect the flux toward the gap ,it can be considered as a shield but quite inefficient. I’m agreed, maybe I was too hasty with demagnetization.



It’s like those magnets are too strong to be shielded.
I just tried it with one magnet from 10`` subwoofer. 2 millimeters steel sheet works, but not as good as I expected. You can try to arrange them magnet to magnet, but at very close distance the motor strength will be significantly decreased.
Right on.. I didn't want to get into a huge discussion on it, but you find magnets close to one another all the time out in the world and they don't hurt each other...

Obviously you know what you are talking about, then you know the inductive magnetic force it requires to charge a magnet.. It's not of this earth..

So maybe if you stuck a bunch of NEO magnets to a standard magnet, who knows.. maybe...

I mean, you know someone with a "box" full of speakers, I'm sure... I bet they all work just fine... :D
 

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Discussion Starter #16
Magnets stuck to one another will be south to north pole, so would re-inforce each other. North to north or south to south is my issue, will over time this lead to weakened force?
 

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not in the proximity they will in to one another..
 

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Yes Sir, but as I mentioned before, you will have the top and bottom plates of the speaker shielding them...

As they sit, as a bare magnet, the field is doughnut shaped.. add to that the top and bottom plates of the speaker and you squish that down a bit farther...




I don't see a problem, but if you don't wanna do it, well, that's up to you..
 
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