Also, any hints as to how make these sound good? I've read that they can be a bit sloppy. I don't need them to be "audiophile" quality since they will be used in a furnished breezeway to supplement some homemade bookshelf speakers that the 7pi's will be replacing.

My plan is to go the Isobaric (sp?) route and I thought about matching them to one of those subwoofer amps available from Parts Express (either that or an older NAD amp I bought on eBay). I don't want to go horn because of size contraints, but I though about a tower configuration to minimize footprint if the required box volume was too high.

Any thoughts?

Can you recommend some signal generation software for the PC? I don't have an oscilloscope, so I'll be restricted to an RMS DMM, but from the research I've done it appears that I should be able to get pretty close.

These are car audio 'IB' sub drivers so OB, very large sealed, or aperiodic is best, with the latter yielding the highest SQ. It's specs are ideal for a 'classic' stuffed TQWT and going isobaric will keep the line's CSA reasonable, so 12" square (inside dims) should work fine and a ~93.63" pathlength will tune it to ~30 Hz if stuffed along its length with ~48 oz of R-19 fiberglass. The beauty of this design is that the specs can be off quite a bit and still perform well by adjusting the amount of stuffing.

Catalog specs:

Fs = 30 Hz
Vas = 6.83 ft^3
Qts = 1.04
Pe (RMS/max) = 75/150 W
sens = 88dB/W/m (+/- 2 dB)
nominal 8 ohms

GM