Yep, it's a mouthfull. But, things are going pretty well so far. A little background first...
My theater (see sig) will eventually be a 7.1 surround setup, with 3 of my unity horns (see sig) for the mains (plus low end woofer boxes, yet to be built), and full range surround speakers. This build pertains to the "4 and 5" channels, or the front surrounds.
Goals and constraints:
1) must be built into the walls with as low a profile as possible.
2) must reach 110 db+ at 1 meter before reaching excursion limits.
3) must maintain a reasonably flat response to at least 10k at listening positions, which are up to 45 degrees off axis from these speakers.
4) will be controlled by miniDSP crossover/EQ
5) must look cool!
So, I came up with an MTM + passive radiator design, which will have ported front plates covering the two woofers. These ported woofers plus the passive radiator will create a dual bass reflex alignment. Right now, it looks pretty boring, but once I have it built into the walls with curved baffle sides and drywall shaping, I think it will command a double take.
Originally, I had planned on a 3 way design, but I decided that I didn't want the expense of another decent driver, nor the added amp channel that this active crossover design would require. That leaves two way variants. At first, I thought that I could get away with a ported low end to the Ushers, but the allure of a passive radiator and no port "mid bleed through" won me over. So, off to WinISD. I chose the Dayton 12" passive radiator for this build:http://www.parts-express.com/pe/show...number=295-496
I already had 4 Usher 8137 drivers (2 for each speaker), so I chose to use them. Zaph's data shows that they have very low distortion to around 1k hz.http://www.zaphaudio.com/8test/compare.html
This, coupled with their relatively low profile and highish xmax (5mm) fit the bill for me. However, to take full advantage of these drivers' distortion profile, I need to cross no higher than 1k hz. Hmm... off to Zaph's site again. This time, I stole his Dayton 8" waveguide plus SB acoustics SB29DC idea from his blog:http://www.zaphaudio.com/blog.html
see Feb 5, 2010
This hopefully will provide both the low crossover point as well as the constant directivity of high end response that I need. I will shape the response curve of the horn loaded tweeter with the miniDSP. Here are pics of what I have so far: pic #1 shows the ground plane layout, and pic #2 shows the two "leaves" of the box apart.