Thanks to the help and suggestions from several guys here, all the drivers are selected so it is the moment to start a build thread. Over the years, I have been all over the place deciding this!
For a semi-dedicated homecinema in a new house build, I want to build all the speakers starting with the center and then the left and right front speakers. Each LCR uses the same drivers, but since the center is put behind the 330 x 140 cm (130 x 55") 2.35/1 acoustic transparent XD screen from Seymour, which is visually floating, the box shape will be different. It is easier to make, so I want to have a go at that one before making the towers.
The room is about 22.8 x 28.4 x 8.7 feet hence more than 5,000 cubic feet. It is a box-in-box construction on top of a floating concrete floor to keep the noise
sound inside. I checked the room ratio at Salford University website and it rates among the "best". Not my merit, just pure luck. I have also been consulting an acoustician to implement room treatments. I fancy diffusion elements which will be used behind the AT screen (flanking the center speaker), on the side walls, the back wall and the ceiling. Then a reverberation measurement will be executed which will enable us to decide on extra absorption, most likely in the bass region.
Two subs are long ready using 18" Maelströms. 550 liters each, "LLT" tuned to 13 Hz. I might add two more (sonotubes) if necessary.
- SEOS-24™ waveguide
- BMS 4594ND coaxial 1.4"
- EighteenSound 15ND930  / or Beyma 18P80Nd 
The idea is to use a passive x-over between the BMS tweeter and mid (@6,300 Hz) and use a miniDSP 10x10 HD as an active x-over between the bass and mid @ 450 Hz since that is where ChopShop has it. The 15ND930 was suggested to me because it is suitable for a lower tune than most pro 15 inches. It is still 98 dB / Watt sensitive which theoretically gets me 125 dB @ 1 meter using the Emotiva XPR-5 (600 Watt @ 4 ohm). That should be enough for our 12 feet listening distance... Acoustic Energy, although specced great, was not a viable option since these do not seem to be represented in EU. Woofers are expensive to ship! The 15ND930 can be had for less than €250 including delivery.
The recommended enclosure volume is 60 - 140 liters (2.12 - 4.95 cu-ft). I made the exercise and I can actually stretch to 140 liter net volume for each woofer (320 liter gross internal with braces before the volume of the drivers and ports are counted for).
Now I have to figure out which tune and what size the ports have to be. Is there Mac-usable software out there? Or is there a good soul who could do the math for me? i would like to try to set the x-over to the subs as low as 45 Hz, the threshold of directivity. Maybe I end up higher, but it would be cool to have the option.
The two L+R towers would be MTM which puts the SEOS-24™ centered @ 1 m height (yes, you guessed it, they are 2 m height). This leaves two options for the center:
- MTM layout which puts the SEOS-24™ @ 1.25 m height. I guess I can tilt it downwards a bit to aim at MLP.
- MMT layout with both woofers on top, which puts the SEOS-24™ @ the same height as the L+R. Is that good practice? If the woofers would have been crossed higher, then I guess not, but I presume I am okay up to 450 Hz? This would be my preferred option.
I would use 30 mm MDF and apply more than enough bracing.
Any suggestions very much appreciated.