Fred, well at least you've been able to make Mark Johnson feel better! On the sharp dips shown, one point to keep in mind is that both the positioning of the sub at a null and the microphone(or your ears)at a null can result in such dips. For example, someone sitting in the middle(horizontally speaking)of a 15' wide room would experience a dip at about 560/15 or 38Hz. Your room dimensions plus sub and ear positioning will change these effects.

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Enjoy the music, not the equipment.