Get it. But still phase plugs are not very common in drivers..Smoother response. Gets rid of what is happening under the dustcap (oil can resonance), and the crap happening inside the dustcap (pushes anything way up in frequency).
Nothing wrong with the box shape, it looks like a really big microTower, (original thread and one of the most recent)
microTower bipolar ML-TL for CHR-70 or EL70
You just need to know that the vent (restricted terminus) will need to be longer than your BR modeler shows. Also being endloaded it should likely be largely filled with damping material.
What is the total box net volume?
Actually they are quite common. And i have not yet met a whizzer coned driver that does not benefit from their addiiton.But still phase plugs are not very common in drivers..