[hjmiller]

Never really got a complete answer on my port sizing questions. Looking at most of the commercial sub designs it seems that for a 12" driver you rarely see any more than 2 - 4" ports. Modeling of my design, using the 17 m/s rule as a limit I show I need either 3 - 4" ports or a single 6" port.

Are the DIYer's in general just more meticulous about port noise than the commerical designs, or is there something else specific about their (the commercial designs) design constraints (smaller boxes typically, maybe less Xmax on the drivers they use?, maybe more liberal use of bass boost to get more output from the driver and less dependance on the port at lower frequencies).