I don't have any fancy equipment either. I have test tones that Randy recommended and I play them from 16Hz to 300Hz in 1 Hz increments and record the SPL. Then I plot SPL vs. frequency in Excel. Now that I have a laptop, maybe I should look into getting some software though.

Make sure you don't change your configuration between measurements. I look forward to seeing what you come up with.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated