Neo's and heat!

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bjm362
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Joined: Sun Aug 31, 2014 5:55 am
Location: Oklahoma City, Oklahoma

Neo's and heat!

#1 Post by bjm362 » Wed Sep 10, 2014 9:34 am

It looks to me like most, if not all of Bill's designs are vented well enough to avoid this trap, but I thought you guys should still be aware it exist.
Commercial cabinet manufacturers aren't generally inclined to inform you of this because the average end user isn't likely to suffer the effects during the warranty period.
Neodymium magnets pound per pound are incredible, we all know that around here! But did you know they are subject to complete loss of magnetism at temperatures that occur frequently inside cabinets under heavy use. BTW, In my experience as an audience member it doesn't bode well for the evening when a system with a pair of W cabs, each with 4x21s start to have problems and the sound guy finally gives in and shuts them down before they completely destroy themselves.
Those weren't permanently damaged, but I wouldn't want to be in even that situation! In a room that is the acoustic equivalent of "The Twighlight Zone" and the key component of your system, allowing you to succeed in this environment is acting like it is going to fail!
Since you guys have already figured out by now that I am just a bit looney, I thought I should include links so you could see for yourself.
http://www.kjmagnetics.com/blog.asp?p=t ... um-magnets
http://www.kjmagnetics.com/specs.asp
Yep at temperatures lower than glue for speaker cabinets has to be rated to (to prevent combustion) Neodymium magnets can fail, and can fail permanently.
Using them in such a menner as to repeatedly get them just below permanent failure temperatures can have a cumulative effect as well. small sectors reaching actual failure temperatures, permanently failing until enough fails that the whole thing becomes useless.
Recone kits do not provide a repair for a dead magnet. Those wonderful lightweight magnets have a dirty secret.
Fortunately for us, Mr Fitzmaurices designs in utilizing technology to couple the rear energy in correct phase with the front energy from the driver while still loading the horn has the added benefit of improving the cooling effect from the waves being produced in the air. There ar some scenarios where I still will not even consider the coveted neodymium magnets. Like I said though, it looks like the BF designs are vented well enough to avoid this hazard, but I thought you guys should still be aware it exists!!!!
Since forewarned is forearmed I thought I would pass this along!
In order to have a dream come true, you must first dream it!

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Bill Fitzmaurice
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Re: Neo's and heat!

#2 Post by Bill Fitzmaurice » Wed Sep 10, 2014 11:59 am

The neo heat issue was long ago solved by driver manufacturers. We've never had a heat de-gaussing issue reported.

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