I am trying to tell the difference between versions 1-4 of PS and PW series subs by looking at the back of them. What versions of PS series subs are these? Do any two versions look exactly the same? What versions of the PW series is this? How can I tell the difference between 1,2, and 3? I believe this is v.4. Am I correct? Some more questions... Why doesn't Paradigm put v.x on their subs like they do other speakers? What was the first year Paradigm made PS or PWs? Does anyone have old catalogs (pdf) of v.1, v.2 or v.2 Paradigms?