When the voice coils are wired in parallel, the woofer presents a 1-ohm load. When the voice coils are wired in series, the woofer presents a 4-ohm load. Infinite-Baffle Operation: The woofer is also optimized for infinite-baffle operation (free-air) so that it can be installed in a variety of locations, including factory woofer applications, without the need for a dedicated enclosure.
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