Audio Fluids
Benefits
Increased Thermal Power Handling
Ferrofluid is roughly 5 times more thermally conductive
than the air it displaces from the gap.The fluid provides a much
lower thermal resistance between the coil and pole/top plate, lowering
the voice coil operating temperature under both transient and steady
state conditions. This increases power handling capabilities.
Damping
Ferrofluid in the gap provides a mechanical resistance
to the moving coil. The amount of damping is proportional to the
viscosity of the ferrofluid.
Voice Coil Centering
When the voice coil is displaced in the radial
direction in the gap, a restoring force is obtained which is proportional
to the displacement. Although this force is a fraction of that provided
by the suspension, it is still enough to influence the centering
of the moving coil. This force constant is given by:
where:
Ms = saturation magnetization in tesla
Hm = maximum field strength in the gap in
ampere meter
h = height of fluid in the gap in meter
t = width of the gap in meter
r = radius of the gap in meter |
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Reduced Distortion
Harmonic distortion and spectral contamination
caused by radial and rocking modes of the voice coil is reduced
due to the centering force of the fluid upon the voice coil. Ferrofluid
in the gap also creates a seal, or liquid "O" ring around
the coil which eliminates air modulation noise in the gap, particularly
within the piston band.
Reduced Power Compression/
Improved Dynamic Linearity
Minimizing the temperature rise of the voice coil
reduces thermal power compression effects. Ferrofluid in the gap
not only reduces sensitivity loss but maintains the linearity of
the speaker's output.
Increased Production Yields
Due to the centering and lubricating properties
of the ferrofluid, manufacturers have reported improvements in production
yields ranging from 30%-60% when introducing ferrofluids into existing
products. This reduction in scrap can often offset the cost of the
ferrofluid itself.
Simplified Passive Network Designs
Ferrofluid's ability to control a driver's behavior
at resonance and, to some extent, break-up modes at the top end
of the pass band, eliminate the need to address these problems in
the crossover network, eliminating the need for additional expensive
resistors, caps and inductors.
Reduced Coil/Magnet Size
A 1" (25.4 mm) voice coil driver with ferrofluid
can achieve the same power handling as equivalent sized drivers
which utilize 1.5" (38.1 mm) or 2" (50.8 mm) diameter
coils. The cost savings from the smaller magnet/coil more than offset
the ferrofluid cost. The weight reduction may also be attractive
in many applications.
Ferrofluid | Vacuum
Feedthroughs | Thermoelectric Modules
Contract Manufacturing | Literature
Rack | Specialty Seals
Inertia Dampers | Electron
Beam Evaporation
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