Magnetism

 

New member
Username: Nmlbasshead

Post Number: 3
Registered: Mar-06
I wanted to know what magnet size had to do with a speakers performance. Does a larger magnet make much of a difference?
 

Gold Member
Username: Mikechec9

Post Number: 2266
Registered: May-05
no
 

Silver Member
Username: Solacedagony

New Jersey US

Post Number: 823
Registered: Oct-04
Magnet size and magnet material affect the strength of the magnet, but individually, this has nothing to do with performance. You shouldn't change the magnet that's on your speaker either.
 

New member
Username: Nmlbasshead

Post Number: 5
Registered: Mar-06
Ok so what does it really matter when they put a larger one on? For example the jackhammer I saw has one around 800 maybe 900. Thats seems like alot of extra weight. I'm not contradicting you but what reason would there be for such a huge magnet?
 

Gold Member
Username: Mikechec9

Post Number: 2268
Registered: May-05
Motor strength, in and of itself, is absolutely meaningless. "B" (flux density) is evidence of nothing without knowing "L" (length of vc) in the gap. So it's the strength AND the ability of the structure to focus "B" over the distance of "L" that's significant. The size of the structure means warm poo.

In fact, the type of metal used will be a determining factor as to how large/small the motor is (neodymium, ceramic...). Most huge motors are primarily, if not strictly, utilized for presentation and marketing purposes. The Brahma, for example, admitedly used an oversized magnet (big 'olbooty) to attract customers. I, for one, would be a huge fan of increasing the motor size as the diameter of the cone is increased. But that's just for proportion's sake.
I just think it would "look" better:-)

As a disclaimer though, Bl should not be solely considered when determining how "badass" a sub is. That's what t/s are for.
 

Bronze Member
Username: Nanbakat

Mexico CityMexico

Post Number: 17
Registered: Mar-06
Travis, you are confusing the term "bigger" with "better". A better magnet would be one that is stronger, not necessarily larger in size. The strength of a magnetic field is measured in Tesla units, abbreviated as "T". Thus, a magnet rated at .3T would be stronger than one rated as .2T.

(If car audio enthusiasts really wanted to compare apples with apples then they would ask sub manufacturers to list the manget strength in their sub specs.)

A magnet with a stronger magnetic field would be able to move a speaker cone more effectively than one with a weaker magnetic field.

For example, a neodymium magnet generates a stronger magnetic field than a standard ferrous magnet which means that you can either:
A) make the magnet smaller to generate the same force on the speaker cone (this is what Bose does in their small satellite speakers)
B) use a neodymium magnet equal in size to the ferrous magnet to generate greater force on the speaker cone.
 

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 11388
Registered: Dec-03
with the magnet in a speaker's motor, bigger isn't always better.
field strength is what matters.
stacking magnets only adds around 10% to the field strength, whereas going to a larger diameter magnet (think voice coil size, like 2" or 3") makes for a much stronger field.
The type of magnet affects field strength as well.
What matters in the end isn't the physical size of a speaker's magnet really, but the Bl of the speaker (a measure of motor strength) and looking at the Qts of the driver to determine if the speaker is over-damped or under-damped.
 

New member
Username: Nmlbasshead

Post Number: 6
Registered: Mar-06
Ok so the bl is the motor strength. I found a sheet on an old junk mtx that puts the motor strength at 19.35 tm is that a decent motor or a cheap one? I'd have put my own speakers up if I could find them so that will have to do as an example. :-)
 

Silver Member
Username: Solacedagony

New Jersey US

Post Number: 834
Registered: Oct-04
Read Glasswolf's last paragraph again.
The Bl is matched to the speaker.
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