Quote Originally Posted by Art J. View Post
My idea then may have come from the Klipsch Cornwall which seems to have a similar
proportion shelf to yours, though my shelf was not nearly that deep or low.
http://forums.klipsch.com/forums/sto...Cornwall15.jpg
Maybe I was on my way to MBR and didn't know it.
The Cornwall has a large duct (shelf) vent to get a low tuning at a relatively high efficiency similar to the Jensen Ultraflex, a crude stepped TL in essence. The double bass reflex (DBR) is two separate vented chambers in series, so if your duct vent came back close enough to the rear wall to air mass load this restriction, then it was a DBR.

GM