Generally, a subwoofer is good half an octave below tuning. Still, it depends on the limits of your woofers suspension, as well as how the box is designed. peace
Just keep in mad, this is "in general" the point to where you'll be fine and have good SQ down to this point. You subwoofer will still be fine, just don't push it too hard below tuning //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif