[pianotech] Increasing bridge height

[Jude Reveley/Absolute Piano]

Hi John,

I'm not sure I can answer this to your satisfaction, but as I understand it, 
the bridge and ribs really play quite a different role than the soundboard, 
even if in the end they function as a unified assembly. Despite past claims 
by Wolfendon and others, for example, that the ribs help to tranmit sound 
across the grain, I don't believe that we hear the vibrations coming from 
the ribs and bridge. In fact I would love to hear a piano that was built 
with just ribs and a bridge(no soundboard), one of spruce and one laminated. 
I would hypothesize there wouldn't be a big difference. Rather, the 
soundboard is the diaphragm that moves the air while the bridge and ribs 
control the impedance of that diaphragm.

Jude Reveley, RPT
Absolute Piano Restoration, LLC
Lowell, Massachusetts
(978) 323-4545

----- Original Message ----- 
From: "John Delacour" <JD at Pianomaker.co.uk>
To: <pianotech at ptg.org>
Sent: Tuesday, March 24, 2009 7:31 PM
Subject: Re: [pianotech] Increasing bridge height


> At 23:29 -0400 23/3/09, Jude Reveley/Absolute Piano wrote:
>
>>As for spruce roots, I'm not sure speed of sound is a factor in range of 
>>human hearing as far as I know...
>
> That's not the point.  The use of spruce makes a good deal of difference 
> to the ratio of volume and mass to stiffness, just as it does in the 
> soundboard, and the speed at which sound is propagated through the whole 
> system most certainly has important audible results.  Why should the ratio 
> of stiffness to mass be so precious in the soundboard and not in the 
> bridge?
>
> JD
>
>
>
>