my subwoofer did not come with the little "ring" that goes between the woofer and the enclosure to make it air tight. what should i use as a replacement? rubber, silicone, ...etc. when my bass hits, i get a little "buzz". it's like a tiny vibration but it distorts the bass sound. i took out the sub and played it out of the enclosure and it sounds fine. so it must be a little space between the woofer and the enclosure when it is mounted in the bass tube.