Data and theory are presented to show how the properties of magnetic fluid (ferrofluid) added to the air gap of loudspeakers affect the driver performance parameters. Voice-coil temperature and transient power handling are shown to depend on the thermal conductivity of the fluid in the gap. The dependence on fluid viscosity of loudspeaker resonance, frequency, mechanical Q, and impedance is discussed, and potential advantages in design are presented. The centering of the voice coil by magnetostatic forces, which can reduce the occurrence of voice-coil rub, is also discussed.
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