I want to upgrade a pair of 4-12 PA columns. These are sealed units. The original worked the speakers in an "acoustic suspension" mode.
What T/S numbers do I need to look at, and what should they be, to get 12" drivers that perform well in the low end in these coulmns. The columns are about 16" x 10" x 53" inside (4.9 cu. ft.), minus a little bracing and 4 small-framed 12" drivers. Since there are no partitions, I suspect that the internal volume should be divided by four.
What Qts numbers, and what values of other perameters, should I look for drivers for low end performace in this cabinet?

Thanks,

Tom