Recommendation after doing a good amount of work with tbe MBM12s in a full range design, with that lower tune and the total output capability of them limited by excursion, to get the most out of your HTM8, consider going with two 12s. The 12 solo is going to run out gas long before the HTM, however having said that if your happy with less than max spl, just put a limiter on your 12 at max excursion (300-400w IIRL) to protect it and level match the HTM. I also agree that crossing the 12 higher at 120-150Hz or so and sealing or raising the tune of the HTM might be a bit more efficient, using the best of all deivers in their wheelhouse.
In any case i really like the design and plan man!!! Ill be following!
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