BTW, I'm not smart enough to figure any of this out... but I have smart friends over at the DIY Audio Forum who provided me with an Excel spreadsheet calculator that does all the math.

I just plug in the height & width of the panel, diaphragm-to-stator spacing, number of wire groups, and the low end cutoff frequency (where the woofer takes over) and the spreadsheet calculates the resistor values, max SPL, and frequency response curve. Pretty cool!