Cones And Dynamics

Well it's not the limitation of planar magnetics. You know that, having Beta's.

>>What physically limits the dynamics in Magnepans?<<

Their efficiency for one thing. Have a listen to some box/cone speakers rated in the low 80's and see what you think.

>>Do ribbons contribute to dynamics in a box speaker?<<

Depends. They do help with the harmonics in the upper freq's.

Even though a planar diaphragm is physically larger than a typical cone woofer, its excursion capability is much more limited in speakers like the Magnepans. Typical cone woofers can move an inch or two to produce their sound while planars are limited to a small fraction of an inch...

So by design, unless you have a planar with huge woofer area, conventional cone woofers work better for bass extension and power.

Large cone woofers do not need large amounts of excursion to produce sound.