Instability puzzler

[Ron Nossaman]

> I'm curious about this also.  What is required is some material that 
> will transfer energy from the strings to the soundboard.  Would wood of 
> any kind work reasonably well for a vertically laminated bridge, 
> assuming there is a traditional maple bridge cap?

In practice, it's not as mystical as people try to make it. 
The bridge doesn't need to be vertically laminated and capped 
- or not capped. It can be solid wood, horizontally laminated 
wood, or a composite.


> Would a bridge made from epoxy work as well as rock maple, ebony, or 
> other choices out there?  (I'm not asking based on workability, but just 
> as a theoretical medium for transferring energy.)
> 
> JF

The Voodoo in this scenario seems to come in with the term 
"energy", implying some mysterious and exotic function of 
molecular level vibration and tiny inscrutable smoke emitting 
demons. In my world, the string moves the bridge, and the 
bridge moves the soundboard. If the bridge is stiff enough to 
spread this movement out beyond a very localized spot on the 
soundboard, this is good. If not, this is un-good. If it is 
made of a hard enough material to transfer the string's 
movement directly to the soundboard rather than absorbing it 
in internal friction, this is also good. If not, un-good. The 
mass of the bridge in any given part of the scale should be 
high enough, given the stiffness and mass of the rest of the 
assembly, that the resonant frequency of the soundboard 
assembly is lower than the string input, and low enough to 
displace by string input with a high enough amplitude to 
produce the required volume of sound. Whatever material(s) can 
meet these criteria, in whatever configuration they are 
applied, should be realistically eligible as potential bridge 
material. The devil, as they say, is in the details, but I 
think the truth is in a relatively few, relatively simple 
basic physical requirements.

The industry, collectively, tends to resist this approach.
Ron N