Guess there is quite a bit to cover, but I'll do my best. Regarding the design with the pair of TD10M's and the NeoPro5i ribbon, I did spend a couple days measuring and designing the preliminary xover. The difficulty with this design vs others is simply that the ribbon tweeter can't be faced upwards. It sags. So to get good measurements with no reflections means putting the speaker up in the air. We ended up getting the tweeter approximately 10ft off the ground so I could get enough distance to gate out the floor and ceiling reflections in the gym I borrowed at church for 2 days. The TD10M does have a sharp peak of 5dB or so about 2500hz. The NeoPro5i has a peak about equal in magnitude at about 1200Hz. My intended Xover region was in the range of 1800-2000hz. Ideally each of the peaks needs a notch filter for the crossover to become more simple if doing it passively. I didn't have much time in the gym though, but using 3rd and 4th order filters you can modify the Q of the filters to somewhat take care of these peaks. That is what the initial Xover does and it works pretty well. If someone wanted to do it actively you'd just need one band of EQ for each of the peaks and things are quite simple after that. My hope was to play around a little more with the cabinet up on the forklift outside. However it seems to have been raining of ridiculously windy for weeks now.
That said, some people feel that the SPL capabilities still may not be high enough with that system. Levels of 120db+ continuous at 1m are extremely high, but who am I to tell someone they can't have more if they want it?
The limiting factor is really the tweeter on the low end. While drivers like the TD12M's or TD15M's will play higher, they do beam more as well at these higher frequencies. The addition of a midrange driver is really the key to unlocking more of the potential from the woofers and tweeter. The difficulty is in finding a midrange that is really ideal and something that will sound as good as the TD drivers covering that range. It's an issue we are aware of and have some things coming down the road for that but it will likely be 3-6-12mos to make it a reality.
In the meantime there are some options to look at. The first one that comes to mind is the 18sound 6ND410. It has a 1w/1m sensitivity of 97.9dB which actually matches the real sensitivity of the NeoPro5i almost identically. Mark has a pair of these and says they are quite nice. So, one of these next to the NeoPro5i and then the pair of TD10M's or even TD12X's would really be an SPL monster.
Then at that point we get into the range where we can start looking at a 1" compression driver on the 18sound XT120 horn as well but that would require multiple midrange drivers and multiple TD12M's to fully take advantage. Personally I greatly prefer the ribbons to the compression driver option. Ah, so many options. The hard part is in coming up with something to make the majority of everyone happy.
Also on a slightly lower cost, lower output version a single TD12M with the 6ND410 and the NeoCd2.0M could be an option as well. RAAL ribbons could be substituted for probably the ultimate in sound, but slightly lower output version than the NeoPro5i.
There are multiple other options that could be thrown in for the midrange. The PHL's, Audax, B&C's, etc. could all be options, but it's looking like the 6ND410 is the best option until we can get some 6" and 8" drivers worked up here.
So here is my initial thought of what to offer. Give me your thoughts and suggestions. The MTM using pair of TD10M's and NeoPro5i as planned before as I already have a few applications for it.
Then a larger version stepping up to the TD12X's and adding the 6ND410mid.
I think as a third final option to save some cost we could look at a single TD12X, the 6ND410 mid and the NeoCd2.0M.
penngray, for your application specifically i think the third option would work as it would fit your left and right and be more along the lines of your initial request. For the center channel I need to do some thinking yet. You could easily use the same mid and tweeter, but with only 9" H we need to figure out something for the woofer section. If only you had 2" more height to work with it would be simple. Let me do a little thinking on that yet.