Have read the threads on roll-your-own cabinets and decided to give it a go. I have used bgavin's spreadsheet http://www.ofgb.org/reference/Musicians Reference.xls along with http://www.kbapps.com/audiodesign/calculators/index.htm and http://xsspl.tripod.com/Audio/KeeleBox.htm to calculate a ported enclosure for an Eminence KAPPA-15LF. I chose this speaker as it looked a good choice from gavinb's spreadsheet and I have found one for a reasonable price . I have got slightly different figures for cabinet sizes and port dimensions from the 2 URL's : I intend to go with gavinb's s/sheet figures and construct a port 5.35 inch dia. in a 5.23 cu. ft. box @ 20.84 in (W) x 33.73 (H) x 12.88 (D). I play a 4 string Precision. I currently do not own a bass amp. Some questions : What technical data should I look for when choosing a mid-range driver to go with the woofer. Can anybody recommend a suitable one (ideally Eminence to match the woofer ?). I intend to mount this in a sealed enclosure above the woofer's ported enclosure and in it's own sub-chamber. I had considered a speaker up to 7kHz could be suitable. What resources exist for designing a crossover or, preferably, can they be purchased off the shelf. I am not technical. What minimum wattage of amp would I need to drive the above driver configuration in a small venue (40 ft x 40ft room size say) and be in balance with unamplified drums. Thanks - I've got to say that this site conatins the best info on speaker building I have found and far outshines some of the speaker makers attempts at building "tips".