Beetle - I'm not sure how much of that is correct - coming from different sources over time. I said mechanical crossover, but was enlightened to the contrary. Also the carbon diaphragm idea was countered by machined aluminum / beryllium alloy. And the sealed bass might have been my speculation based on my knowledge of Jim's fundamental bias. I never spoke with him about it, and my input comes from three sources with their own reads on the prospects. Even though his illness was kept secret from all of us, he knew he was dying; so the 7.3 may have been mostly speculative. But it seems it was what he was working on at the end.