Here are my favorite links for making what I do reproducable: http://sourceforge.net/projects/speakerworkshop/ http://www.tolvan.com/ http://www.artalabs.hr/download.htm http://www.audiotester.de/ http://redspade-audio.blogspot.de/2010/12/how-to-measure-your-crossover-with-holm.html http://www.linearteam.dk/ http://www.ht-audio.com/ http://audio.claub.net/software/kougaard/ubmodel.html Feel free to add other links. Please avoid Forum links. While there is a lot of info that can be gleaned, it is tough to tell the difference between personal opinion and "reproducable in my living room". There are some pretty hair brained claims about bass extension - especially with efficient drivers.