Quote Originally Posted by VolvoHeretic View Post
I've been doing some thinking... Just how does Altec use the same frame and wind up with speakers that have such a wide difference of Xmax? 416-8B; .13", 418-8hII, 421-8HII; .05" (?), I could go on, but how do they accomplish this?
Very belated reply, but xMax doesn't really address the frame. It is how far the coil can travel without leaving the magnetic gap. Altecs are underhung, meaning the coil is shorter than the gap Just for the sake of argument, assume a gap length of one inch and a coil 1/2 inch. Past 1/4 inch in either direction the coil leaves the gap.

Overhung OTOH uses a short gap and long coil...attempting to keep a constant number of turns in the gap. Most consider overhung not as linear.