The Theater three π cabinet is a Helmholtz resonator, just like any other bass-reflex cabinet. The alignment is specified by PiAlign, and the values it specifies are not unlike other common alignments.The Delta 12LF is best used in cabinets from 2.0ft3 to 6.0ft3, tuned between 30Hz and 40Hz. EBS cabinets can be a little larger, tuned lower for the bass shelf. But in general, there are a continuum of good alignments in this range.
A PiAlign'ed Delta 12LF has a slightly overdamped response, with useable response down to 30Hz. Like the PiAlign'ed Delta 15, this gives bass with gradual rolloff slope and slightly rising response. That makes them perfect for use in corners or as floorstanders against the wall, where room gain might make some speakers tend to sound boomy.