DIY subwoofer design FAQ ...For getting you newbies started I'll start the list of topics in no particular order...after we get a list, we can get the data rolling (IMO). 1) "What the heck does that mean?" ...a Glossary Of Speaker Terms. 2) What type of subwoofer setup? (sealed, ported Etc.) 3) sealed varients: IB/Linkwitz Transform/ELF (EAS)/isobaric 4) ported varients: PR/TL/4th order Bandpass 5) What makes a good enclosure? 6) What makes a driver more suited for particular alignments 7) There is no replacement for displacement (the nature of SPL) 8) How low is low enough? 9) What is room gain? 10) basic/advanced modeling software (FREE!!) 11) The various Qtc's of sealed allignments 12) The various ported alignments 13) Should I brace? 14) proper tools and TOOL SAFETY 15) Can my driver be used for downfiring? 16) Efficiency and Sensitivity 17) Everything Sonotub 18) Can my XXX brand car audio sub be used for HT? 19) What if I don't have T/S parameters and no actual speaker measuring software? 20) How does a port work? this should keep you all busy for a while. My advice is to use already posted info instead of re-creating it. But, you BETTER SITE IT and give the author due credit !!!