This is just idle speculation but here goes. The Walsh (Ohm?) driver was a huge cone, specially constructed. I've never heard one, but I understand it was quite spectacular. As I understand it, sound waves travel across its surface and launch at different places, shorter wavelengths where the cone's diameter is related to a wavelength I guess. As designed, the waves launch from the "outside" of the cone. Very well. But what if the cone were more of a horn/waveguide: Would the waves then launch from inside the cone? Has this ever been tried? Would each frequency launch at a different distance? That would make time-aligning the speaker a chore, I'd bet. 😱