So the B&C website was down this morning when I went to look up the T/S parameters of the 21 SW152. So I went to "the Google" and quickly found a thread by Josh Ricci, who is contributing to this thread, on building his 21 SW152 speakers:
http://www.avsforum.com/avs-vb/showthread.php?t=1240709& page=1
Quickly skimming the thread, it appears that one of the papers on port behavior in my AES library (that I paid good money for!) is available for free on the Harman website:
http://www.harman.com/EN-US/OurCompany/Technologyleadership/ Documents/Scientific%20Publications/11094.pdf
If you try to access the root directory, though, it appears to be password protected. It appears Harman is perhaps better at building speakers than playing administrator on Apache...
Regardless, this a long (27 page) paper on ports. JBL/Harman typically has excellent technical papers, and this is no exception.
Cliff Hendrickson, Doug Button, Mark Ureda, and Don Keele--all JBL/Harman guys--have collectively authored a great library of AES papers on all things loudspeaker design.
As a PS in appreciation of the LAB community, I could not believe how unruly the thread on that "AVS" forum appeared to be. Thanks for being civil everyone!