Vertical directivity is determined by the spacing of the drivers, their coverage patterns and the crossover frequency, phase and slope.

You can always put the drivers on a baffle, then measure to find the appropriate crossover points and slopes to put the nulls where you want them to be. Of course, you have to be in the ballpark when positioning the drivers on the baffle, but the end result is determined by the overlap frequencies and phase, which is set by the crossover.

• Baffle spacing, phase angles and time alignment, revisited