box tuning

[madscientist 0]

So I am thinking of venturing into unknown territory and build my first ported box. I have been doing a little research but am still learning.

As I understand it, frequencies below the tuning of the box can cause the driver to "unload" which can cause damage. I am not 100% sure what that means, but I digress. I have read more than a few threads that say they tuned their box to 32 Hz and then go on to say that the low-end is amazing. Now I listen to mostly rap music, and it seems like to me that there are a lot of songs with frequencies below 32 Hz. There are a couple low notes in Jeezy's "Hypnotize" for example that I am guessing dip below 32 Hz. How is it that the box can still safely play these notes, and better still have them sound amazing? Am I missing something? Does it have to do with the subsonic filter keeping the driver from unloading, and yet still being able to reproduce these frequencies without the cone ripping from the surround? Or am I completely off and I just am confusing what certain frequencies sound like?

[helotaxi 46]

Actually there is very little musical content below 32hz in most any music. It's out of the bandwidth of TV and radio broadcasts and therefore misses the target medium. Compared to a sealed box, loud in the 30s in really pounding out the lows. Most people don't know what 30 hz sounds like.

As far as the sub being able to play lower than the box tuning, it will, to a point. The problem that you run into is the air in the port which provides the majority of the output at tuning, very quickly gets out of phase with the sub below that and starts to cancel out the subs output. The effect becomes more pronounced the farther below tuning you go. It will provide output below tuning it just won't be as loud.

Final thing, a box designed using 99% of the software and equations out there is designed without accounting for the effects that the cabin of the car will have on response and actual enclosure tuning. You actually want to tune a few hz higher than desired because the cabin effect is going to lower your tuning a bit.