I built a 4th order passive sub to go with a pair of bookshelf speaker for Music Only. It is based on 2 peerless 830668 and i found impressions similar to Brian's INF10. I want to build a notch Filter to clean out of band noise. Is it advisable to put the filter only on the external woofer (the one facing the vented box)?Moderated By: brian@diysubwoofers.org