basementjack, yep, that's how I heard about it... Basic progression was:
Plan to build ported HT sub.
Discuss designs, review specs, discuss at AVSForum and some other DIY places and realized I needed some sort of EQ &/or HP (rumble) filter to make sure I don't kill my drivers below tuning and insure I get the smoothest results above tuning for my room..
Looking for solutions, BFD was mentioned... Price was right via eBay, new for $78 shipped..
All good info on the BFD leads here and to REW.
Now I'm here, and need to drop some more $ on an SPL meter, unless I can find someone who lives close by to lend me theirs for a few days...
Anyway... just chasing another rabit down another hole... deeper, and deeper...