What are fluid-filled (fluid-cooled, ferro-fluid) tweeters?
These tweeters are built almost exactly the same as other tweeters. They look and act almost exactly the same, too. The only difference is that they have a small, controlled amount of a special fluid inserted into the gap between the magnet and the voice coil. One big effect of adding this fluid to a tweeter (or to any speaker) is that it makes the voice coil capable of dissipating more heat. This means that the speaker can have a lighter voice coil, for better performance, or a higher power rating for the same voice coil. The other big effect of this fluid is to add mechanical damping. The frequency response and transient response of the driver will change, possibly for the better. In addition, this fluid may help center the voice coil, may lubricate the voice coil, and may help keep dirt out of the gap. This fluid will not increase the magnetic field, concentrate the magnetic field or otherwise change the magnetic circuit. Nor will it cushion impact if the voice coil bottoms. The flu
