How much to magnet B deteriorate with time?

[ocool_15]

I don't think I've seen it brought up much.


Does a Ferrite or Neodymium strength degrade over time significantly? If you have a driver say 5 years old is it safe to say the motor strength is basically the same as new? What about 10 or 15 years?

[Dirk]

They'll stay magnetized. UNLESS they get too hot that is, but we're talking, like, "soft enough to be malleable." I imagine the voice coil will let go first.

[Jeff B.]

I don't think I've seen it brought up much.


Does a Ferrite or Neodymium strength degrade over time significantly? If you have a driver say 5 years old is it safe to say the motor strength is basically the same as new? What about 10 or 15 years?

We use some sensors at work that use Neodymium-Iron-Boron magnets because they are spec'ed to only lose 2% of their field strength over ten years. Apparently AlNiCo magnets hold up well too because I recently measured some 1979 JBL woofers whose T/S parameters were still almost identical to what the 30 year old literature said about them. Ferrites are the cheapest and least dependable to the magnetic materials. They will not hold their strength for as long as the rare-earth magnets do. However, they are still adequate for how we use them in speakers. I have some Focal drivers that are over twenty years old and they still measure the same as they did many years ago too.