Mounting magnet to magnet, possible issue?

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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.
 
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.
 
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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.
 
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"
 
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There is a BIG dfference between sounding smart and actually being smart.

Hi, sadly that is very true, and your a fine example, rgds, sreten.

In fact your not doing a good job of sounding smart, nevermind being smart.

I severely doubt Adelaide Speakers use the poor principles you advocate.
Of course I've never heard of them, and of course there is no mention
of such practises on their website, so your just being disingenuous.
 
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Of course we are. With between us Edward & I have only 65 years of experience building and selling loudspeakers to 3 and a half thousand customers world wide so what would we know?
"Considering themselves wise in their own understanding they became utter fools" I understand that for lesser souls knowledge can lead to conceit. The more I know the more I realize how little I truly understand and how much more there is to know.
 
Up until around the early 2000's Scanspeak sold backing magnets for quite a number of their loudspeaker drivers. So why don't you contact Scanspeak Streten and tell them you are so glad that they stopped that idiotic practice of selling backing magnets to IMPROVE the performance of their loudspeakers.
 

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Lastly I will add that I proved the lowering of the driver QTS with a pair of Vaf 151's. They were excellent speakers from the get go with Seas drivers & 2mm dia wire hand wound air core inductors. I took them to Adelaide speakers to see if they could be improved further. 3 Neodymium magnets were added to the bass/mid and a new crossover designed for it.
The new design lowered the QTS to the point where it no longer worked sealed and needed a small port.
I then took it to Vaf to get Philips opinion. That was obviously before he sold the Vaf name. I wanted to compare them to the new 191's. They couldn't get rid of me fast enough as some potential customers were much more interested in my 151's thinking they were a new improved model to replace the 191's
I simply smiled took my speakers and left. I always rerget selling them but got a gushing rave +ve feedback on ebay.
 
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The Neodymium magnets I can get out from China if I buy enough cost me depending on currency fluctuations & the price peaks & troughs for Neodymium between $5 & $7 Au landed per slug as pictured above on the B110. I have found quite the opposite to be true. But in the interests of keeping the peace I will refrain from answering any more questions unless it is related to assisting in answering the original poster & his magnet to magnet question that has been answered in full by previous posters. My sensei always said it is shameful to combat unarmed opponents
So in this battle of wits circus sideshow I apologize for contradiction of my bushido code.
 
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