I will say, after several different attempts at tuning the box that there are a couple of things that *must* be done to get the box to line up correctly.
The easiest thing to screw up on these are the crossovers between the different drivers. Get the timing as close as possible and live with the phrase wrap. If you don't have FIR, it's better that everything lines up with what's next to it than making each band generally start at the same time.
The coaxial drivers benefit greatly from some out of band boost to flatten the response before applying the 6.5kHz crossover between them, as well as between the HF and the 12" mids. You'll find that some small variations in the delay between the two coaxial drivers are extremely beneficial. The 9kHz region will need some love, and I find a small amount of boost around 12kHz and above can help out. You'll find a dip in response somewhere above 2.75kHz that never quite evens back on the lower coaxial component - fiddling with a couple different combinations of filters yields a good result that interacts with the VHF nicely. I don't have mine up at the moment, but Peter's from page 11 of the 60 degree thread give you the general idea. As I have the 60 degree horn, I do not know if this applies to the 90 degree horn much. I will say that I wholly disagree with Peter's choice to reverse polarity on the VHF component. I think it sounds like absolute garbage, but maybe there's some secret I don't understand.
As far as the 12" mid section goes, I have yet to come up with great settings. I do not have a place to test them where they don't have reflections from several things, and you really have to move your measurement mic around the pattern to get an idea of what the mids are *actually* doing. Mine aren't anywhere near as directional as the horn, and integrating the two patterns has been difficult. I'll be honest, I haven't had too much success yet, but getting the crossover alignment right is the difference between the box sounding meh and sounding really clean.
Oh, yeah - one more thought. I'm using an iNuke NU4-6000 and a DCX2496. The only problem here is that the iNuke has a voltage gain of above 70x and the particular DCX unit I have seems particularly noisy. With a cabinet this sensitive, I suggest you are more careful than I am in choosing your amplification and processing sources. I get very audible noise from the system at the moment, and it's all my fault (I'm cheap -sue me).
