I've had my UM18-22 in a 4 cu ft sealed box for about 4 weeks now. Break-in was a long process as I had to do so in my Edge at about an hour a day. In the past week or so it's totally grown on me. I finally got around to using the Auto-EQ on my PRS80 (the difference in phase/imaging was night and day - I find myself changing the rest of the eq based on the music I'm listening to anyway). At any rate, I'm amazed by the subs ability to seamlessly blend into the front stage. I regularly forget how big it is, till I go to put groceries in back. I'm really curious what the 4 cu ft ported would sound like, anyone else gone that route? I popped in an old Bass Mechanic CD from IDK like 1996 the other day (circa my SPL160 & Reference 700 days) and heard a some frequencies I'd never "felt" before. I went with 4 cu ft based on pe's recommendation.
Sealed (home theater/music): 4 cubic ft. (net internal, not including driver) for an f3 of 31 Hz, f10 of 18 Hz with a Qtc of 0.72
I've got two Rockford T1D412's sitting in my living room in the "recommended" sealed enclosure, that are getting rather lonely. Sadly, I guess I've grown up and don't care for the rockford's sound anymore? Although, if I had a large slot loaded box for them I'd swap them out on the weekend when "sq" isn't on the agenda, just stupid loud bass.
My next project I hope, is removing the floor in the back of my edge and working in a second UM18-22, thinking I could get close to 8 cu ft and gain some trunk space (who need's a spare right?). Just haven't worked with glass in a decade, and no real shop or garage that's heated to work in.
I'm always on a tight budget, I think these are a great value. My home reference for sound is a 1990's Altec 305A's set with an Atlantic Technology sub I picked up from pe for a steal a couple years ago, running off a Sony STR-DA4ES.