Hi all, After building the AA Tempest, I noticed I still have a bit to learn about building cabinets... (you might remember the cabinet I used developed some kind of crack / became unglued). The sub still works like a champ in my music-only system, so I'm very excited about my next project. I was thinking about starting small this time. Since the drivers I have available have a large Vas (198.6L), low Fs (22Hz), low Qts (0.384), Qms=13.36, Qes=0.396, and nice Xmax (17mm) (yeah, the old HED-12's I have in storage), I have two choices: 1. Build a big (150L) cabinet, or 2. Build a 75L isobaric subwoofer. Since I just got married, option #2 seems nicer and nicer.... I understand I'll lose 3dB when compared to a single driver big cabinet. I think I'm willing to make the trade-off, considering we (my friend, the carpenter and me) will get much needed experience in building speaker cabinets before trying to rebuild my AA box (yeah, I'll do so as soon as I can!). I was thinking about building an isobaric vented sub. Sadly, I have just realized this is a lot harder than I thought, especially when considering I'd need pretty big ports, or go with a 3" one. So I'm leaning towards isobaric, sealed, with a slight (+3 dB) bass boost. I'll probably move the subwoofer to a bigger box when I'm ready to do so, anyway. I have also been reading about compound subs. While I think I do understand the mechanics behind isobarics (lose 3dB's, cut box size in half, basically), I haven't been able to find much info about compound units. I think MartinLogan uses this configuration on their high-end hybrids, but that's as much as I know about this. If anyone can suggest how to proceed, or have any ideas on how to better define this project, I'll be very grateful. At the moment, I think the limitants are: * Small, easy to build box * Low Fs / F3 * Not much SPLs required - as long as the sub goes waaay down deep. Thanks!