Hmm... so figure a one-way limit of 38.1mm for the LMS then.
According to what I've been reading, port compression begins to take affect at 10 m/s, becomes noticeable at 17 m/s, and becomes a real hindrance after 26 m/s. When using the passive's one way excursion for xmax as an equal comparison to port compression, it's clear the PR
enclosure saves a ton of space, over 50%.
I'm going with an 8.2 ft3 enclosure and two mms-maxed PRs powered by the EP4000 with about 1900W RMS and 2500W max into 4 ohm bridged, I believe. That'd get 13.78 Hz tuning, 116dB@16 Hz, and 117dB@20Hz. This should get the audible range right up there with two sealed LMS's.
If I need more SPL down the road, I can drop the mms and get the CV-5000 amp with 5000W max, for 17.24 Hz tuning and 121dB@20Hz, at least on paper so to speak.
The wood's already been cut and having the holes CNC cut tomorrow.
EDIT: Thanks mjaudio. I'm getting the PRs for a buck each. Two sealed would clearly have tons more SPL in the upper frequencies, but that range would all get EQ'd down for flat in-room response. The real trade off for the bass reflex is losing tons below the tuning frequency, <12 Hz region in this case, but I'm ok with that. Plus I'll use half the power of two sealed.. Uh scratch that, I'll be consuming less than 1/4 the power because it would take more than the difference in power to cool the additional heat in the room.
The PRs are allowing me to tune super low with a large enclosure which drops delay well below the sealed alignment so transient response should be better, not that it would be at all noticeable in these frequencies with the sealed LMS being so good as it is. I could be wrong and I'd just be out some wood and half the cost of the PRs after selling them.
A little OT but I'm also excited to be getting 3 Hypex nCore NC400s for my LCR now that my 7 channel amp gave out one of it's channels recently.