Voice Coil Motor aka VCM aka Voice Coil Actuator
- Low to no hysteresis
- Zero cogging
- Fewer mechanical components
- Linear control characteristics
- High power to mass ratio
- High power to volume ratio
- High acceleration
- Where precision linear movement is required
- Where precision force is required
- Where oscillatory motion is required
- Where Dynamic Movement is required
How it works
By driving a current through the voice coil, a magnetic field is produced. This magnetic field causes the voice coil to react to the magnetic field from a permanent magnet fixed to the speaker’s frame, thereby moving the cone of the speaker. By applying an audio waveform to the voice coil, the cone will reproduce the sound pressure waves, corresponding to the original input signal.
The actual wire employed in voice coil winding is almost always copper, with an electrical insulation coating, and an adhesive overcoat. Copper wire provides an easily manufactured, general purpose voice coil, at a reasonable cost. Pure copper in its International Annealed Copper Standard (IACS) as 100% IACS = 58 MS/m at 20 °C, decreasing by 0.393%/°C. Where maximum sensitivity or extended high frequency response is required from a loudspeaker, aluminium wire may be substituted, to reduce the moving mass of the coil. Aluminium wire has about one third of the mass of the equivalent gauge of copper wire, and has 61% of the electrical conductivity. An aluminum conductor’s cross-sectional area must be 56% larger than copper for the same current carrying capability.
Pride car subwoofer voice coils are made of CCAW Copper-clad aluminium wire, allowing easier winding and a useful reduction in coil mass compared to copper.
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