Mass Loading Bridges

Ron Nossaman rnossaman@cox.net
Sun, 05 Feb 2006 10:46:00 -0600


> Ron,
> I have a Erard with a new board that sings beautifully...except for the 
> last 1/2 octave. Fudging with the hammer placement has yielded only min. 
> improvements. It almost sounds as though the board is stifled in that 
> section. Thus the idea of mass loading the bridge has me thinking in 
> those terms.
> 
> Tom Servinsky


Hmmm, could be a number of things, but something is sucking up 
the string energy. Sounds like you've eliminated the usual 
suspects by plucking and strike point prospecting, so it's not 
the hammers. I'd try a big vise grip on a bridge pin up there 
to see if you got any positive change from the added mass. If 
so, then you get to try and figure out how to get to the 
underside with weights - unless the vise grip can be gold 
plated and sold as a feature. Try wedging blocks or a screw 
jack under the belly rail too, and see what that does. Better 
yet, jack a hunk of steel, lead, brass, or whatever you have 
at hand that is heavy against the underside of the belly rail. 
If you get a positive change with any of this, it gives you a 
diagnosis of sorts, and at least a chance at improving it.

Luck,

Ron N

This PTG archive page provided courtesy of Moy Piano Service, LLC