Mass Loading Bridges

[Tom Servinsky]

Ron,
I did experiment by pushing down on the bridge and I believe there was an 
improvement. You are correct about the limited access to the treble side as 
there is hardly any room to even get to the underside of the board.
Tom Servinsky


----- Original Message ----- 
From: "Ron Nossaman" <rnossaman@cox.net>
To: "Pianotech List" <pianotech@ptg.org>
Sent: Sunday, February 05, 2006 11:46 AM
Subject: Re: Mass Loading Bridges


>
>> 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
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