I am wondering what are free air subs. I saw some enclosures for them and i want to do one for my civc because i like them alot. I was planning on getting two alpine r 12's but i dont think they are free air. I am just running crappy lightning audio in a huge sealed box right now. I was wondering who makes good ones and can you guys recommend any. I am definately looking for two 12's. Also is it possible to hook all 4 of my speakers to a 2 channel amp? thanks