My Regina 15.5" music box has a cast iron bedplate.  If I understand it,
what is theoretically required of a music box bedplate is high stiffness
and low mass.  The high stiffness efficiently transmits the vibrations
to the case.  The low mass allows a larger amplitude to be transmitted
for a given amount of energy from the tooth.

Did all music box manufacturers use cast iron? It has high stiffness,
but also relatively high mass.

Aluminum has much lower mass, but is not as stiff.  Still, it seems that
an aluminum bedplate with stiffener ribs would have been better than
cast iron.

Any thoughts on this?

Wayne Finger