[CAUT] Soundboard mass

[Ron Nossaman]

> Anyway, I'm wondering if others have done similar things with similar
> outcomes or found that bridges below a certain height simply don't have
> enough mass without some help.  Further, with a certain minimum bridge
> height does mass loading become unnecessary?  

I think it's stiffness, rather than mass that makes the most 
difference in the taller treble bridge. Addition of mass 
doesn't typically do much good for the classic killer octave, 
but mass loading a treble that is too stiff and screaming wild 
with short sustain helps considerably. It's a resonant 
frequency thing. 
http://www.kettering.edu/~drussell/Demos/SHO/mass-force.html


>I've often wondered if the
> early Steinways with bridges under 30 mm in the treble (and sometimes well
> under) don't compromise those areas by virtue of inadequate height and
> therefore both mass and stiffness to begin with.  

I'd say so. That and the compression crowned boards.


> Moreover, is there what one would consider an ideal bridge height?

You can get away with a shorter bridge with more ribs, where 
fewer ribs need the added stiffness of a taller bridge. One of 
those "it depends" sort of things - again. Assembly stiffness, 
mass, and frequency response requirements are the thing, and 
variations on proportion among the assembly's parts can 
average out similarly in practice. The rules are different, 
naturally, in different parts of the scale.


> BTW Ronsen Bacon hammers with plenty of power (after a more refined filing
> in the treble) and warmth!  No lacquer, no plastic!

MMMMMMMMMMMMMMMmmmmmmmmmmmm, yea.
Ron N