I am considering building a pair of mid-bass reinforcement speakers but am not quite sure of the best way to proceed. I already have the drivers, a pair of Cetec Gauss 12", 4ohm woofers that I had in my car in the late 80s. They have been in the closet since then & I would like to see them breathing again. I can find most of the Thiel-Small parameters and I think I can figure out the enclosures (sealed?, ported?, size? etc) but I haven't found what feels like a good option for x-overs and amplification. I could take the passive x-over route but I would prefer to go active. Any good suggestions on either a plate amp or external x-over and amp combination that won't break the bank for this "experiment"? I guess my price point might be around $500, which is about half the cost of simply buying a pair of HSU MBM-12's. Thanks for any available help.