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Wayne, Saw these on ebay and I was considering bidding on them. I'd like to build some sub-cabinets, ideally to cover from 25/30Hz on up to about 150/180Hz. Would these be a good starting point? Thanks
Absolutely, the JBL 2241 is an excellent woofer. Not only is it good for clubs, theaters and other large venues, but actually it is very well suited for use in smaller and medium size rooms when installed in 8-10 cubic foot cabinets tuned to 30Hz. The response curve is slightly overdamped and has deep bass extension, making it conjugate room gain nicely to generate very deep bass.
Would these woofers work well in your corner loaded designs? Also how do they compare to 2242's?
That alignment is perfect for Pi cornerhorns. It has deep extension, and is slightly overdamped, just exactly what you want. Go for it!
How about some 300B 8W tubes? Think I can get some delicious sound out of that combination.
Re: Ok...what would you drive them with?
That'll be enough for a small room, under about 500 square feet. At maximum output, it's about 107dB at 39" (1 meter) distance. Double the distance, subtract 6dB, i.e. 101dB @ 6.5 feet, 95dB @ 13 feet. You might want to use more power in larger rooms, maybe a plate amp for the bass bin and your 300B's for the tops.
What cabinet dimensions should I use? How do I go about finding out port size?
Referring back to the drawing of the Pi cornerhorn in the PiAlign document, the bass bin motor chamber should be 46" tall, 24" wide and 12" deep. The port should be 4" diameter and 1.5" long. The woofer should be centered horizontally, offset slightly below center vertically and the port should be below that, centered in the space that remains. Put a pair of cross-braces, one pair spanning side to side, and the other pair spanning front to back. The top pair should be placed 1/3rd the way from the top, the other 1/3rd the way from the bottom. Each brace should fit snug, providing a little bit of force on the panel. Put R11 or R13 insulation inside on three sides, either left or right, the bottom and the face side opposite the woofer cutout. Also hang a sheet across each brace, spanning the cross-section of the cabinet. The insulation isn't required for a subwoofer or bass bin, provided midrange is not presented to the woofer. But this cabinet does run up into the midrange, and the insulation damps internal standing wave modes. It attenuates midrange standing waves but bass passes right through.