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Mounting magnet to magnet, possible issue?
Mounting magnet to magnet, possible issue?
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Old 17th August 2016, 04:18 PM   #1
JamesBarr is offline JamesBarr
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Default Mounting magnet to magnet, possible issue?

Hi All

I am designing a subwoofer and I was thinking of mounting the drivers magnet to magnet with a piece of rubber between them, bolted together with threaded M5 rods that goes through the enclosure. To make everything as stiff and stable as possible.

Would there be any problems of the magnets interfering with each other when mounted like this? I can feel the magnets pushing away from each other obviously, but I'm still unsure if that's a problem when their mounted symmetrically/coaxial like this.
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Old 17th August 2016, 08:29 PM   #2
zettairyouiki is offline zettairyouiki  United States
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Depending on the driver, a lot of them sortof "pump" air through the center of the magnet on the back to keep the voicecoil cool. Clamping two together could defeat that mechanism and lower the long term power handling of the drivers.
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Old 17th August 2016, 08:42 PM   #3
JamesBarr is offline JamesBarr
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They have a solid backplate, it's a pair of XLS Peerless 830452. But thank you tho
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Old 18th August 2016, 01:05 AM   #4
sreten is offline sreten  United Kingdom
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Hi,

No problem at all.
They will act like bucking magnets for each other, reducing
external field and slightly enhancing the flux in each driver.

rgds, sreten.
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Old 18th August 2016, 04:40 PM   #5
JamesBarr is offline JamesBarr
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Thank Thank you sreten ��
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Old 19th August 2016, 12:54 PM   #6
mwmkravchenko is offline mwmkravchenko  Canada
Mark Kravchenko
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Mounting magnet to magnet, possible issue?
Quote:
Hi,

No problem at all.
They will act like bucking magnets for each other, reducing
external field and slightly enhancing the flux in each driver.

rgds, sreten.
+1

With one caveat. If they are touching you might want to put something soft in between them to stop potential rattling/knocking sounds.
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www.kravchenko-audio.com
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Old 20th August 2016, 06:16 AM   #7
theaudiopath is offline theaudiopath  Australia
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I use neodymium backing magnets all the time to mod various drivers. You need to orientate the magnets so you get some initial resistance before they stick. Otherwise you will be having the magnetic force of one cancelling out the other. Which will entirely defeat the purpose of adding them in the first place.
Cheers
I will also add that neodymium magnets are so powerful they stick like gorilla snot and I've never had them move aside from where I add more than 4 slugs where they have to be glued with an industrial epoxy to prevent their combined force from repelling each other. Also if you add that many you are lowerng driver qts significantly so a sealed driver may now work better in a ported TL or even in some extremes in a horn. Stock Qts of .21 or less will have limited beifit from adding magnets as it is already close to the limit of practicality.

Last edited by theaudiopath; 20th August 2016 at 06:27 AM.
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Old 21st August 2016, 01:58 AM   #8
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by theaudiopath View Post
Also if you add that many you are lowerng driver qts significantly so a sealed driver may now work better in a ported TL or even in some extremes in a horn.
Hi,

I would argue you cannot lower Qts significantly, all you can do with
backing/bucking magnets is cancel exterior field outside the magnetic
circuit. I haven't thought about totally overdoing it which I guess you
could with neodymium magnets as a very inefficient way of using
the magnets, with an absolutely huge exterior field equivalent to
any gap flux increase then induce into the magnetic circuit.
If its already saturated, your totally wasting your time.

Bad design practice, there are much better ways of doing it.

rgds, sreten.
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Old 21st August 2016, 07:50 AM   #9
theaudiopath is offline theaudiopath  Australia
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Bad practice? One of my modified Tannoys using exactly this mod is earning it's keep in Paul Blakey's mastering studio. Since its installment not one track had had a return for remastering.

"Wisdom is vindicated by her children"
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Old 21st August 2016, 10:20 AM   #10
theaudiopath is offline theaudiopath  Australia
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REALLY! Edward Rotgans of Adelaide Speakers uses this "bad design practice" on nearly every single one of the 3300 + loudspeakers he's designed & built. In 30 years he has had only 4 returns.
There is a BIG dfference between sounding smart and actually being smart.
"Wisdom is vindicated by her children"

Last edited by theaudiopath; 21st August 2016 at 10:23 AM.
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