Aluminum dome tweeter utilizes
ferrofluid for damping/cooling and increased power handling.
Ferrofluid is put in the space between
the permanent magnet and the voice coil of a speaker. Heat flows from the high
current voice coil and into the ferrofluid. When the ferrofluid is heated above
its Curie temperature it is no longer attracted to the magnet and is pushed out
of the magnetic gap by cooler fluid nearby. This forms an active, liquid, heat
pump to prevent damage to the speaker. (Wikipedia)
