Mechanical wave propagation (diffraction / reflection)

[thadman]

Excuse me if this question is obvious.

Do mechanical waves propagate through loudspeaker diaphragms (whether they be elastic or rigid) in the same way that acoustic waves propagate through waveguides albeit a different medium? As far as I understand, reflections occur at the boundaries of the diaphragm due to a similar mechanism (an impedance mismatch) in the same way reflections occur at the mouth of a waveguide.

Assuming this is true, where would the source of the mechanical wave occur in a driver where the motor force is distributed uniformly over its surface (ESL/Ribbon) and for a driver whose motor force is not distributed uniformly (Dynamic Cone)?

Could diaphragm geometry be conceived in such a way to optimize its mechanical diffraction / reflection pattern to minimize and distribute the energy over a wider bandwidth?

Thanks,
Thadman

 

[neurosport]

Do mechanical waves propagate through loudspeaker diaphragms (whether they be elastic or rigid) in the same way that acoustic waves propagate through waveguides albeit a different medium? As far as I understand, reflections occur at the boundaries of the diaphragm due to a similar mechanism (an impedance mismatch) in the same way reflections occur at the mouth of a waveguide.

All correct so far.

Assuming this is true, where would the source of the mechanical wave occur in a driver where the motor force is distributed uniformly over its surface (ESL/Ribbon)

There is NO wave in this case, at least if the edge is not clamped. If the edge is clamped then it will be a source of a wave of reverse polarity to the original.

and for a driver whose motor force is not distributed uniformly (Dynamic Cone)?

The voice coil / former.

Could diaphragm geometry be conceived in such a way to optimize its mechanical diffraction / reflection pattern to minimize and distribute the energy over a wider bandwidth?

hm ... i think Manger was trying to do something like this ?

Also what is usually done is the edge is damped by corrugations. Most JBL PRO drivers have this.