Quote Originally Posted by GM View Post
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

Hi GM, I was hoping you would chime in. I meant to say DBR not MBR.

I kept my shelf to a minimum trying not to effect cabinet volume but still being
effective at controlling turbulence. Less than half the depth.

The un-even loading was very apparent with the dual woofer design like
the Altec Malibu that we talked about before. The woofer closer to the port
had more excursion than the other. The shelf would help to even the loading.

I smile and always knew this was crude experiments, living on a shoe string in Engineering
school. I had more ambition than resources. It was a great time.