Speed of driver and Stif Here is a gif from ora graphene q kickstarer page used to illustrate the stiffness of their graphene diaphram. What they are actually demonstrating is driver break up but it's still related and sorta illustrates what i mean by "moving through the driver" A dynamic driver is pushes its diaphram in the center with the motor. The stiffness/(speed of sound) determines how well the diaphram moves together. The middle of the diaphram starts moving due to the motor, that movement propagates to the rest of the diaphram at the materials speed of sound. DISCLAIMER: All the stuff i am saying is just things i picked up here and there so i could a bit off on my a few things.