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Old 16th September 2008, 12:44 AM   #1
skooter is offline skooter  United States
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Default Magnets, Magnets,Magnets!

why do some subwoofers have big magnets and some have small magnets. does this make the woofer move harder and quicker! Like a new coustic crusher 12" has a 25oz magnet, and the MA audio XQ series 12" has a 60oz magnet.
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Old 16th September 2008, 04:55 PM   #2
amc32 is offline amc32  United States
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The choice of motor structure is "basically" based on factors of meeting x-max ideals -vs- motor strength (gaus).

There's no one factor that makes or breaks a speaker design,they are all compromises.

And all ideal factors can be taken into account in the design of at the exspense of final end cost.

A instructional book on speaker design,not just subwoofers,is Loud Speaker Cookbook,Voice Coil Magizine and the likes
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Old 16th September 2008, 10:17 PM   #3
jol50 is offline jol50  United States
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It is a whole balancing act: you have a mass for the cone and if you increase it for strength or lower Fs, you need more magnet/motor to move it and more suspension to control it. Then you need more voice coil to handle more power and you get inductance, and need more suspension to handle the power while all that lowers efficiency. Now you have high xmax drivers and the issues they run into....anyway, every time you change something you change the balance between those things and change the response and efficiency of the driver.
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Old 17th September 2008, 03:10 AM   #4
ppia600 is offline ppia600  United States
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They need to just give in and use neodymium on all decent subwoofers. I'm tired of waiting, lol
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Old 17th September 2008, 06:00 PM   #5
jol50 is offline jol50  United States
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Quote:
Originally posted by ppia600
They need to just give in and use neodymium on all decent subwoofers. I'm tired of waiting, lol
Would be nice. When I put my subs in I about freaked out when I installed the loaded baffle in my trunk, talk about heavy.
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Old 17th September 2008, 08:41 PM   #6
Flyin11 is offline Flyin11  United States
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From what I remember, the bigger the magnet = more power. For example...A sub needs a big magnet to be able to handle 800W of power. That's what I remember being told a while back anyways....

The MA Audio sub with the 60oz magnet would be able to handle more power than the Crusher that only has a 25oz magnet.
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Old 17th September 2008, 08:53 PM   #7
shagone is offline shagone  United States
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Quote:
Originally posted by Flyin11
From what I remember, the bigger the magnet = more power. For example...A sub needs a big magnet to be able to handle 800W of power. That's what I remember being told a while back anyways....

The MA Audio sub with the 60oz magnet would be able to handle more power than the Crusher that only has a 25oz magnet.

Not Really. it depends on the design and structure of the voice coil and suspension as well. sometimes the huge magnets are overkill and just for looks. if the voice coil and suspention cannot handle the stresses of the input power they will fail either electrically or mechanically. ie shorted/blown voice coil or torn spider/surround along with broken wire leads. i've seen all of the above but never a magnet damaged by too much power. i have an MTX Thunder 6000 12" sub in my garage right now with a relatively small magnet but the design is well ballanced and makes a decent sub with decent power handling.
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Old 17th September 2008, 09:24 PM   #8
jol50 is offline jol50  United States
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I look at T&S specs, but from the old days it seemed like a heavier cone required more motor to move. Heavy cone was lower Fs.
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Old 18th September 2008, 01:51 AM   #9
ppia600 is offline ppia600  United States
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Neodymium are more powerful for their size. There used to be expensive subs with them back in the late 80's/early 90's but they didn't catch on. You can actually use a very tiny neo versus a huge strontium/ferrite magnet.


eminence apparently has a few, this magnet is only 4 ounces!

http://www.eminence.com/guitar_speak...0&SUB_CAT_ID=5
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Old 23rd September 2008, 06:07 PM   #10
Clipped is offline Clipped  Thailand
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the mags have to be strong enough to permeate the top plate.
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