I was wondering how store subwoofers can achive super deep bass for such a low price with minimal enclosure. For example svs sb 1000 pro declars to hit 20hz -3 which seems quite off with that size. Other example would be emotiva rs 13 which is ported but they delcare 16hz -3 with again small driver. When I tried simulating some drivers in enclosers for example 18" ultimax which got quite high xmax it still requires huge ported box to get down to that sub 20hz. And sealed has problems below 25hz and it's still big.