i know that a ported box at his tuning frequency is 3dB louder than an sealbox, thus for exemple a ported box tuned at 30hz will be 3dB louder than a seal box playing the same note of 30Hz right? so my question is what about the other frequencies like 40Hz or 50Hz? will they (ported and seal)be the same louder at those frequency? or the Ported box will be louder at any frequency? thanks
the ported will be louder at all frequiencies above and at tuning. below tuning the ported will roll off quicker but i think the ported will still be louder than sealed a good ways below tuning. others could give you a better answer though.
Ported will be louder over all frequencies, but loudest at its tuned frequency. but cannot play anything lower then its tuned frequency. sealed boxes usually peak around 50Hz, where a ported box will peak a little higher then its tuned frequency.
a ported box can play well below its tuning frequency but you'll need to set the SSF properly so you dont over excurt the sub. once you drop below the tuning frequency the bass will rolloff alot quicker though.