As you may have read in my previous thread, I bought an Alpine type R off Ebay, and it blew out on me for some reason I think I might've turned my bass up to high, but I still love it and plan on getting another one soon. The box I had it in was a Subzone vented 12 inch box, however I did happen to hear it in a Q-Logic QLH-1.2512SS, and the bass seemed to be a liiiittle deeper. Although I still loved the way it kicked bass out and started an earthquake in my car all the time, the bass that was coming from my Subzone box seemed to be the same. Basically, the high bass sounded the same as the low bass (but the sub still banged out) but I noticed that with my Subzone box, there was a lot more of air coming out of the vent than in the Q-Logic QLH-1.2512SS box. I was wondering if I need a sealed box to hear the different bass levels? What do yall think? By the way I have an Alpine MRD-M605 amp. A local car audio dealer told me to make sure my subsonic filter on my amp was turned on, which I think it already was. But what do yall think about the boxes? I know the Q-logic box is more expensive than my Subzone box. Should I get a sealed box, stick with the same Subzone I have? or upgrade to the Q-Logic QLH-1.2512SS box?