I figured it’s about time to update this thread:
As previously mentioned, this speaker was built for a friend who imposed a requirement that the speaker pair had to fit into his 2008 Audi for transport. Hence; the OB bass section.
I had so many reservations about the design that I was hesitant to post anything more about it until I had confirmed that it works. The low-qts woofer on an OB was a risky choice; giving priority to blending well with the ESL at the expense of requiring separate subs for the bottom two octaves—but my friend has DSP and awesome subs, so it’s not a problem.
In the end the speakers turned out esthetically gorgeous, and thanks to some really smart people on the DIY Audio Forum who helped me along the way, they sound really nice too. The video link below shows the speakers playing this past week at the 2018 Carverfest retreat in NC. They made a big hit and the Bobfather (Bob Carver) raved about them. https://youtu.be/67Flmub-dYo