I snagged this from the Lowdown Sound Club thread but thought it deserved some further discussion. Based on my own experience with mid-loaded cabs and several builds with Eminence Kappalites, I think this idea would work nicely. Here is a sketch of the cab I'd like to try, based on the Eminence website medium vented design. The single tri-port has a bit more cross section area than the 25.12 sq-in of two 4" circular ports and would work better with the driver layout shown. http://www.eminence.com/pdf/Kappalite_3015_cab.pdf The Kappalite 3015 with this loading should really punch with lows that are solid and clear but not too deep. I like this voicing for my 5-string basses. I also like the idea of a switch to run the 3015 woofer either full range for a darker vintage voicing or mid-loaded for a more modern extended-range voice. It's like having two different cabs in one. Two of these would make a monster modular stack. From its response curve, I think this Faital 5" driver would be a great match with that woofer. http://www.faitalpro.com/products/LF_Loudspeakers/product_details/index.php?id=101010100 It's pretty flat between 1-2khz with a dip between 2-3khz and a rising response from there, peaking just shy of 6khz. Nice. A mid driver 2-3dB less sensitive than the woofer pairs well as seen with the 93.6dB Alpha-6A/95.5dB 3012LF (Fearful 12/6) and 95dB Faital W6N8-120/97dB Custom Eminence 12 (Baer ML112). The 8-ohm equivalent sensitivity for the Faital M5N12-80 (99dB at 12 ohms) is about 97.5dB. This is a little over 3dB down from the 3015 (100.8dB at 8 ohms) which ought to match well with good presence without being too much. One of the key components is the crossover and I'd like to open it up a bit here. I'd like to see a low/mid crossover point high enough to let some of that grit starting at 1.1khz through but low enough to limit the rise of that 1.1-2.3khz swell to about 2dB so it's slightly smoother but with that extended mid/high response. Would a 2nd order crossover at 1.5khz provide this or should it be a bit lower around 1.1 or 1.3 khz? If someone would be willing to have a look at this and post some crossover response curves that would be great. Also, when choosing components for a crossover do you use the Re given with the TS parameters rather than nominal impedance, and is a Zoebel network to keep woofer impedance flat around the crossover point a worthwhile improvement to add?