In-wall subs are a fast growing category, and BG has its own wrinkle on the concept. The company's new BX-4850 in-wall subwoofer consists of four modules, each of which contains 12 micro-woofers. One of these modules is shown in the photo. The four modules may be positioned together in the room or separately, and an on-wall version may also be made available. The 12 micro-woofers are each separately enclosed and face each other in pairs. The bass generated by them fires out from the center of the array, through the opening between the left and right sets of drivers, and into the room. Mechanical vibrations are largely cancelled out due to the opposing drivers, minimizing the transmission of bass into the walls, which can muddy the bass and transmit low frequencies to the structure of the room and into other parts of the house.