It only makes this sound when it's hitting lower frequencies hard. How do I stop it from trying to do anything less than 45 or so hz? The subwoofer is an energy es-10. It's about 10 years old. If anyone has any info at all that can help, it is much appreciated. http://www.youtube.com/watch?v=_XhB5MmHWp0&feature=youtube_gdata_player