I've noticed most pa speakers have subs with accordian surrounds and minimal excursion. I'm refering to speakers that would have something like 2 15"s 2 mids and a horn. I haven't seen as many decicaded subs boxes like 2 18"s but they seem to use the same types of drivers also. It seems to me that high excursion subs we use in our homes would work better for them but thats why I'm asking.