That's right, John, but I didn't want to add to the confusion. A very few subs have a separate high pass filter on their speaker level outputs, fixed roughly(very roughly)around 100Hz. However, this has nothing to do with the low pass filter control on the back. Again, the frequent usage of the incorrect term "crossover" for the low pass filter leads to a fairly common misunderstanding that it's also a high pass filter to mains connected to the speaker level outputs, creating a crossover.

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Enjoy the music, not the equipment.