Hi, guys - just wanted to note that differences in closed box, ported and passive radiator design are mostly back pressure on the woofer and compliance of the air inside the box. As the woofer vibrates to create sound from electrical charge of voice coil it has the compliance of air inside the box resisting it. A ported box has less resistance, so sort of flops around and hard to control. A passive radiator design is not so "loose" since you have the suspension of the passive radiator adding to compliance of air and should be more articulate than the ported design. The closed box is best for control however...
I think someone mentioned earlier that they didn't understand why Jim Thiel used the passive set up instead of closed box (With the exception of his subwoofers) and it seems to me he was trying to minimize the size of the cabinet and achieve a deep, well defined bass for the size.
Sorry if I am reiterating something everyone here already knows....
