Demodulation ring solution can offer many advantages in terms of harmonic distortion reduction for high power 18in woofers. In this paper is shown a circuit approach to evaluate the effects of aluminum short circuit rings properly shaped to improve woofer performances. To find the Laplacian force that acts on the voice coil the proposed approach make use of the partial inductance calculation method  to evaluate the distribution of eddy currents into the massive ring aluminum conductors. By partitioning the conductor into cells and by modeling each cell by an equivalent circuit, this method can give results showing a maximum error equal to 6% by comparing measurements to simulations.
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