In response to Wayne Fingers's question as to the feasibility of an
aluminum bedplate in a music box.

I don't know much about the theory involved in these things, but about
six years ago I was somewhat successful in making a cylinder music box
using aluminum for the bedplate.  It is a fairly good sized movement
with a 13-inch cylinder of 2-inch diameter, and a comb of 121 teeth.
The overall size of the bedplate is about 6 inches by 20 inches, and it
is machined from a 3/8-inch thick plate of 6061-T651 aluminum.

The bedplate has three legs that rest on the soundboard, and it is
connected to the front and back of the case in the traditional manner.
The music box sounds pretty good, but I have heard many cylinder boxes
that sound better.

This was only the second music box I have made (the first has a brass
bedplate, but the comb teeth are wider than normal creating an unusual
tone quality), so I have no way of knowing if the tonal deficiencies
are due to the aluminum material of the bedplate, the comb tempering,
the cylinder cement, the case acoustics, or any other factors that were
not fully under my control.

Theorists and physicists will debate the issue of whether aluminum is
as good as cast iron or brass for music box bedplates, but I think that,
no matter what the numbers say, the only true way to satisfy our
curiosity on this issue is for some industrious member to make an exact
aluminum copy of a cast iron bedplate from an existing music box, and
then mount the parts on the aluminum bedplate and listen to the music.
Maybe two identical Reginas with similar tones can be compared side by
side.  Any takers?

It makes more sense to me than all the number crunching that this
question is sure to inspire.  Nothing written on paper should answer
this question to everyone's satisfaction; because, after all, it is how
our minds interpret perceived vibrations that creates quality of sound,
not how the numerical equivalents of those vibrations behave in
equations.

Charlie Hind