I am installing 2 Orb's Audio speakers on a client's boat. There is no space for the subwoofer. I'll have to make myself an enclosure for a bass loudspeaker. I have 6" high clearance 22" wide clearance and 6" to 8" deep . I can then make a "trapezoidal" box. Can anyone help me for the dideal speaker, dimansions and how to build a cross-over for the Orbs? I read somewhere that the actual frquency they were outputing is 180H and not lower as sometimes advertised...Thanks.