2x18" + 8x8" = any ideas? Happy New Year!

2x18" + 8x8" = any ideas (re-posted cos I got title wrong!); Happy New Year!

Hello; Happy New Year! (& a very merry birthday {31'st Dec} to me... )

I've been doing ebay...

got a couple of 18" Proel 400W 96bB/W drivers & eight 8" Wharfdale 2074H 16 99 drivers.

I want to make a fast & accurate sub to accompany a dipole line array (don't ask - tch!) that will ideally cover 15 - 40Hz at 100dB without self-destructing at the odd transient. Nominally, 20 - 40Hz needs to be flat* & very pure, although I DO wish to know if someone's bothered to include the tallest pipe in the program. Not planning on replicating any serious detonations other than the occasional 1812... A/V need not apply.

I've thought of various configurations ranging from sealed 18" - forget the 8"-ers; sealed 4-in-a box 8" (20-40Hz) + ported/sealed 18"-ers (just the 10Hz - [Behringer limitations!] - 20Hz); sealed 18" + ported/sealed 8"-and-live-with-huge-distortion-that-I-won't-hear-below-20Hz-"IF"-it's-in-the-program-material; isobaric 4x8" + 18" (either way BIG space between front & back, SMALL resistive space for back), and finally isobaric/reflex whereby the rear driver(s) are ported & tuned to circa ~ 18Hz.

I don't have loads of space, can avoid WAF; but needs to be sensibly portable (don't intend hanging around with the neighbours too long...).

*I can accomodate 2/3 active x-over points (courtesy Behringer - got 2 DCX2496's, & a DEQ2496 will level the field - sorry analogue purists, but this is an EXPERIMENT!!!) and don't worry about the amps - ebay shall provide...

Anyone got any ideas I haven't thought of?

Hapyy Newt (HIC!) Yurrr!!