prefab boxes are not what is the ideal enclosure 99.9% of the time. they are either tuned to high of too low, not enough or too muvh air space, not built very sturdy, or the MDF is not thick enough which falls under the sturdy category.
it is always better to build a box from scratch to the sub's specs. that way you are ensured that the box is tuned correctly(if it is ported), built sturdy, and has the proper airspace.
"ABC" is Aperiodic Bi-Chambered enclosure. It's basically similar to a bandpass box that allows you to tune ports to two different frequencies so the sub has efficiency peaks at two points instead of one. if you do a search on ABC here you'll find old threads where we'd gone into more detail on ABCs.
