Although the project design is fairly unconventional, I was determined to complete it within a week—including time for glue to cure and paint to dry.

Finding 6" I.D. Schedule 40 PVC was not difficult, and it is typically available in 10´ sections for a reasonable price. I purchased a 4 ft. x 8 ft. sheet of 3/4" MDF for the enclosure end caps and standoffs, although the required parts could probably be obtained from a smaller 2 ft. by 4 ft. sheet. Also required: #10-32 x 2" long machine screws with nuts and washers (get at least 40), #10-32 T-nuts, an 8 oz. bottle of Gorilla Glue, paint, and a scrap 4 ft. section of 2" x 4" stud to align the three tubes while the Gorilla Glue cures. The Model 200 Jasper Circle Jig and a router are the easiest way to cleanly and accurately cut the end caps.

I chose adjustable 1-3/8" diameter port tubes for the woofer modules, with a tube length of 8" achieving an enclosure tuning frequency of 40 Hz and yielding an F3 of 50 Hz. This may not be optimum for maximum low end extension, but seems to be the best trade-off in terms of group delay, and vent air noise (the only noticeable air noise would occur at 20 Hz with power levels of 100 watts RMS per cabinet). This tuning frequency also provided a moderate 2 dB boost in bass response.