THE BOX Using subwoofer tuning software I made this beast of a box for my Rockford Fosgate subwoofer. It's tuned for around 38Hz in the main area and 32Hz in the second chamber. If your not familiar with subwoofer tuning it's essentially calculating volume, hole diameter, and tube length. You can even get real technical, and make two chambers, and tune each to a specific frequency. When listening to music there will be increased output at these frequencies. Get LOW. When you drive your speaker below the tuning frequency the port allows the driver to unload so that it can move much more in each direction with less power, thus making it very easy to push the driver past its mechanical limit. You'll notice in Sound Quality people that they will tune their box to a low frequency like 28Hz and very rarely run their sub below this frequency, so the driver rarely unloads. If I remember correctly anything below 26 is ridiculous and is near sub sonic limits of most equipment. Sound Stream is one of the few amps that can handle low low freqs. But anyways I digress. In SPL people will tune to a higher frequency like 40-42Hz and run their sub below the tuning frequency ALOT, moving more air and thus sounding LOUDER yet worse. Most Hip-Hop/Rap is played with notes in the 40-45Hz range. Club music or any good playlist that takes advantage of the sub is usually mass produced in the 40-50Hz range. Tuning to a lower frequency is best if you want to keep the subwoofer from blowing. Music in the 28-32Hz range is common still and can sabotage a subwoofer if repeatedly exposed to those low freqs.