are you trying to fit an existing enclosure? i built a modified version of this http://www.hometheaterhifi.com/volume_6_3/diy-11- sonotube-subwoofer-september-99.html, i think the secret is to tune the port a step below the fs of the woofer, the woofer i used was 19hz, i tuned one port to 17hz. the port resonates with the woofer an actually stops it from moving, resulting in a breaking effect, resulting in excellent extension (mine flat to 13hz), but also excellent transient response and phase coherenceModerated By: brian@diysubwoofers.org
