i've had rockford hx2s 12s in a small sealed box.....should have better SQ than he2s in a bandpass..and there was absolutely no sound quality. rockford subs are definately not made for sound quality

bandpass boxes are about as sloppy as they get in my opinion

ALL THINGS BEING EQUAL AND THE SUB ACTUALLY BEING ABLE TO GO IN A SEALED AND PORTED BOX THE PORTED BOX WILL BE APX 3db LOUDER. SO IF SPL IS ALL YOU ARE AFTER GO PORTED. ION THE OTHER HAND IF YOU WANT SOUND QUALITY YOU NEED SEALED. I DO NOT WANT MY BASS SO LOUD THAT I CAN NOT HEAR ANYTHING ELSE. I HAVE HAD SEVERAL SYSTEMS AND THE ONLY ONE THAT WAS PORTED WAS MY FIERO BECAUSE THERE WAS ONLY ROOM FOR ONE SUB IN THE CAR. SINCE THEN I HAVE ONLY HAD SEAL ENCLOSURES. THEY DO NOT SOUND BOOMY LIKE A PORTED BOX DOES. NOW IF YOU ARE GOING TO GO PORTED THEN YOU MUST BE VERY CAREFULL FIGURING THE VOLUME OF THE BOX. THE YOU MUST SUBTRACT THE VOLUME OF YOUR DRIVER. THEN YOU NEED TO FIGURE AT WHAT FREQUENCY YOU WANT TO TUNE THE BOX AND THEN GET THE CORRECT DIAMITER AND LENGTH PORT. JL AUDIO HAS MOVED AWAY FROM THE NORMAL PORTS AND WENT TO SLOT PORTS. THIS HELPS TO REMOVE THE NOISE THAT THE PORT MAKES. SEALED BOXES ARE ALOT EASIER TO BUILD AND TUNE. ALL YOU HAVE TO DO IS MAKE IT THE RIGHT VOLUME TAKING INTO ACCOUNT THE DRIVER.

Ports sill make noise and kill the sound waves at extreme volumes, but yes they will get you a 3db gain over a sealed box. A bandpass will get you 3db over a ported likewise. These are figures based on just box design. Most subwoofer drivers are made to be sealed and/or ported. Bandpass roll off very nicely for the crossover on their own, but they are very peaky for sound. Higher notes (60hz and up) are ptretty much non-existant in them. If you know how to use a parametric EQ right, then you can tame them, this is how i had one in my old car.

Slots are very turbulent btw, when was the last time you saw a square TB?

i have never used a bandpass box. i know they are louder but they are bad for sound quality