Age Weakening Magnets

It's possible, but awfully rare. I suppose if the speakers used low quality material for the magnets, they may be more susceptible.

A sharp impact can demagnetize them. If the speakers were dropped on a hard surface, that could be responsible.

how much energy is needed to manufacture a magnet in relationship to the energy it emits?

Magnets do not "emit energy".

Commercially produced magnets are typically magnetized inside an electromagnetic coil -- a solenoid. The electrical power requirement varies. For example, http://www.maginst.com/capacitive.html

Maybe only for "Rare Earth Magnets"?

Heating up a magnet is a sure-fire way of encouraging loss of magnetism.

Once liquid, forget it.

Once liquid, forget it.

Well actually berfore a liquid state. It depends on the amount of Fe and Mn. In low alloy Cs the temperature at which it loses all magnetic fields is around 1400 degrees F (1% Mn). At that point it transforms to austinite.

Ron

Useful to know. Thanks.

Compare it to a metal spring: If you keep the keep the forces that interact with the spring (Expanding and retracting) within the limits of the spring material elasticity, the spring will keep performing the same way almost indefinitely ... Forget metal fatigue for this comparison because the magnet does not have that issue (or at least we assume).

therefore, if you keep the current (which is alternating audio frequencies...) within the limits or below the original current that were used to produce the magnetic field in the magnet, (i don't know to what ratio??), the magnetic field should be maintained the same and not really age. (I stand to be corrected in this issue since it is a not so well common a subject.)

i'm not nessessarily referring to a speaker magnet, but magnets in general.

Frankly can't be bothered after the last attempt to try explain it again. But by all means go and have a look at that flat earth farce.

If you follow and read the links studiously - particularly mine - the fallacy of what someone told you, may become clear.

Any magnetic material has a loss of magnetisation with temperature.

Part of this is linear, so recovered at cooling down again, the nonlinear part is lost.

So quality magnets are once heated to 30°C above maximum usage temperature either by the producer or by the user!

Only Samarium-Cobalt magnets with some Gadolinium added have near zero TC of demagnetisation but somewhat lower remanent flux density Br.

EHABE

My professor was once asked " when a magnet is placed on the end of a conveyor it does work; ( by deflecting the trajectory of the steel bits ) how come it doesn't lose its magnetism?

His answer

" It's atomic energy."

Interesting blog, it made me aware that I know HOW to use magnets, but I still do not understand WHAT magnetism really is......but I am getting there slowly!!

As an aside to the interesting comments posted with regard to magnetism and heat, years ago I used to use quite a good soldering iron where the tips consisted of a magnet embedded in the base of the tip. The tip was also stamped with the temperature that that particular tip would run at as when the correct temp was reached, the magnet, which had pulled a rod in when cold and connected 24 volt power to the heating coil. AC I believe.

Once the set temperature is reached, the magnet loses its magnetism, which causes it to releases the rod, which opens the contacts, the power is removed from the heating coil and the iron starts to cool down. Then the magnetism returns, closes the contacts and places power back on again.

The ones I used came from Weller....they were really good.....

it's my understanding that energy energy can only be converted, meaning the amount of enery used to produce a magnet should me equal to the energy that the magnet can produce. there must be a finite life span i would think, but i've never heard of a magnet losing it's power over time under normal conditions. it's got me baffled