The subject of driver spacing in the link is interesting, tho', cause of the way some of us just perch horns on top of the box. I would imagine, with Pro 4Pi components, 2226 and DE-250, we can look at the Pi Pro4 box and get a sense of proper spacing?

What about those of us that depart from the 2.5 cu ft box and use a 3 or 3.5 cu ft 3677 or a clone thereof like my BatSpeakers?

(Hold on a minute while I measure my speakers...)

...It's 18" from center of woofer to center of comp driver with horn/driver on top. The baffle is 24x32. Does the new crossover have a different effect? What would be the optimum spacing for the 24x32 baffle?

How different would the sound be going from 3.5 to 2.5 cu ft?

When will they find UBL?