Dear @drbond : lewm posted " You want a steep slope on the low pass filter going to the subwoof, because you don’t want the subwoof contributing to midrange ..."
Normaly subs comes with 12db/18db filter shape and the users always can change the low-pass frequency that at the end the sub internal dsp will tell us and through listening tests we can confirm is rigth or we can play with the sub crossover set-up characteristics till we are satisfied with. The Velodyne low-pass shape by default is 24db ( steep as lew posted. ) but selectable and its high-pass shape is 6db. My old Velodyne low-pass filter shape " initial 12db, 48db ultimate ", is what I read in its manufacturer specs.
In the other side, adding sub’s in any room/system means too that maybe we can need some kind of different room treatment maybe not or we can find out that we need to move a little the main speaker positions.
Subwoofers per se is not a " key on hand " solution to open the " door ", we always need some kind of work for the room/system good integration.
R.