Bill, totally open to your feedback. One thing I’m wondering about is if the vibrations from the upper bass are making their way to the midrange. You can feel them through the metal frame.Surge, you don't wanna be showing this stuff to Bill. He has a bad tendency to eat, sleep and dream all of this.
However, the RCA drivers are very solid, heavy, and robust. I have opened and serviced them.
And Jeff Jackson used a metal frame for his $300K(?) flagship horns: