Planar Speaker Asylum

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Planar Speaker Asylum

RE: I agree, and worse

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In Reply to: RE: I agree, and worse posted by DrChaos on January 19, 2011 at 12:00:00

It could be done with the QR foil but it would require much stronger and MUCH costlier magnets. And since he just said they are in a life and death struggle to sell their product as is and that they consider "tweaking" a dangerous extreme that threatens the existance of the company it's not gonna happen.

It's all about the music...

Follow Ups:

RE: I agree, and worse - josh358 16:17:49 01/19/11 (4)
I think I've read that neodynium magnets cost about 50% more. But I gather from something Wendell said somewhere that the problem is that they'd have to use mechanical magnet placement, which has to be costly for a company with small production runs of multiple products. There could also be considerations of physical strength, they might have to increase the strength of the whole pole assembly. And there are reliability questions as well, if neodynium magnets lose their coating they dissolve, this is a problem with the old Monsoons that use the Eminent drivers, the plating starts to come off the magnets and the diaphragms hit it and they buzz as if they were delaminating.

Just read that the big new push-pull module from the BG people, which uses neodynium magnets and achieves 100 dB sensitivity (!) as a result, requires a 4-ton press for assembly.

These things always look easier on paper . . .
- RE: I agree, and worse - grantv 07:26:03 01/20/11 (3)
  In manufacturing a 4 ton press is very small. You know the little "bottle jacks" for $15 at your local Princess Auto, they usually run 10 tons minimum. Our break press here at my day job is 275 tons. Our punch press is 400 tons IIRC. So a 4 ton press to install magnets doesn't seem all that crazy to me.
  - RE: I agree, and worse - josh358 08:23:49 01/20/11 (2)
    What I can't figure out is why they need a press at all. Shouldn't all the forces in a push-pull planar magnet assembly be attractive? Or is the press used to insure that the two halves don't slam together, meaning that the press is working as a pull, so to speak?
    - Guessing only.... - grantv 08:40:52 01/20/11 (1)
      I'd imagine the placement for the magnets is CNC cut into their panel. It's likely a "light press-fit" (perhaps with some epoxy to aid in holding them in place) hence the need for a press of some sort.
      - RE: Guessing only.... - josh358 10:18:50 01/20/11 (0)
        
        In Reply to: RE: Guessing only.... posted by grantv on January 20, 2011 at 08:40:52
        
        Well, I'm definitely getting senile, I remembered it as a four-ton press but in fact it's 12:
        
        "As both Wisdom Series driver types incorporate a push-pull magnetic motor system, the brute force necessary to assemble a driver with opposing magnetic motors and pre-energized multiple magnets is indeed substantial � a twelve ton press is required."
        
        http://www.wisdomaudio.com/pdfs/Wisdom-LS3_LS4-Nov-23-2010-PR-FINAL.pdf
        
        Some interesting info in that press release, including the fact that they use the neodynium magnets only in the high frequency section.
        
        Here's a picture of one of the modules:
        
        http://www.stereophile.com/content/planar-wisdom
RE: I agree, and worse - DrChaos 13:40:57 01/19/11 (1)
Yeah, the price of neodymium magnets are going up like, oh a Chinese rocket?

Apparently there's 1kg of neodymium in each Prius, and Toyota is Not Happy about the situation.
- RE: I agree, and worse - Satie 09:01:45 01/20/11 (0)
  Now Neodymium is doing great. My metals broker wanted to get me into neodymium ingot last year, but the vault operator didn't let him store it. But I told him that the standard precursor to metal would probably have a ready market. So he got into Neodymium oxide and is making a mint. The Chinese export restrictions are making for shortages. I did not take a stake in the trade, but held on to my irridium, which is used to process lithium for gadget batteries.

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