Help with a two way open baffle hybrid

[el capitan]

My plan is to make a 2 way design with four of these in parallel for 4 ohms in an open baffle line array because of their high qts. They would have a sensitivity of 94 dB.

I also intend to use either one of these in a ported enclosure 0.6 cu ft with a 2" diameter port by 5" long to reach 45 Hz with a sensitivity of 86 dB or one of these in a ported enclosure of 1.3 cu ft for an f3 of 55 hz or so with a sensitivity of 93 db.


The first question I have concerns the baffle. Is there an accurate way to calculate baffle size to attain a certain frequency? Ideally I want the natural extension of the fullrange to go 20 to 30 Hz below the crossover point. Given that the fullrange's fs is 135 Hz, is it reasonable to expect to have them flat to 150 Hz with the open baffle, then cross over to the woofer at 170 or 180 Hz. Also, does the baffle have to be flat? I have read about H frames and U frames, and it seems like it is a space efficient way to get lower response.

My other question is about the crossover. I have read some other threads and I got several answers, but do I need any baffle step correction in the network?

Thanks to all for your advice,
Alex