Like morik said, there isn’t much you can do about the ~67 Hz null. However, I’m concerned that something else is going on. According to Paradigm’s web site, your sub should be good down to ~22 Hz, but according to your measurement you’ll be doing good to get 30 Hz, even with equalization, before response falls off drastically. You might try a corner location, if one is available. Also, be sure you had the Radio Shack meter set for C weighting and the calibration file loaded.