On the DIYaudio site you can checkout Dave D.'s (Planet 10) comments in the Loudspeaker thread on the Northwest DIY event in Vancouver last fall. One thread reference is:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=45268&perpage=10&pagenumber=3

See post #24.

Dave also had a post on this area last week on the same subject. See

http://www.diyaudio.com/forums/showthread.php?s=&threadid=51613&perpage=10&highlight=wr125&pagenumber=4

Post #32.

That will get you going. Likely you can find others by searching.

Jim