Soundboard Construction Methods

[John Delacour]

[ I don't see the point of these personalized subject headers, which 
destroy threading, and have therefore changed back to "Soundboard 
construction methods" -- properly spelt this time! ]

At 20:44 -0800 28/1/08, David Love wrote:

>...The question is more one of stiffness, or as has been mentioned 
>by various people, the relationship between stiffness and massÑat 
>least in certain parts of the scale.  As I see it, compression is 
>used to achieve stiffness, or resistance to deflection, and 
>therefore is a means to an end, not the end in itself.

At 21:47 +0000 26/1/08, John Delacour wrote:

>By contrast, other methods shrink the board with the main purpose of 
>achieving considerable compression across the grain of the board in 
>the strung piano, this compression being an end in itself apart from 
>its other mechanical functions.


This is the main big question to my mind in this discussion of 
soundboard construction techniques, which I limit to soundboards of 
spruce, not to muddy the waters with laminated panels, which are not 
at issue here, or with any construction of my own.

By the nature of the barred and crowned soundboard, no matter how it 
is constructed, there will be compression ( or, in extreme cases, a 
reduction in tension!) at the top of the system on the one hand when 
the necessary radial pressure of the strings comes into effect and on 
the other as the moisture content of the board exceeds the moisture 
content at assembly.  What distinguishes the various methods is the 
_degree_ of compression and in particular its proximity to the yield 
point of the wood across the grain.

I will draw an analogy with the stretched steel string where the 
sound of the piano is created, without making any connexion between 
two very different phenomena -- steel under tension and softwood 
under compression -- except to note that the strain to which the two 
materials are severally subjected has important implications for the 
way they vibrate.

As regards this phenomenon in relation to the strings, there will be 
little dispute here, but when it comes to the desirability, degree 
and results of that strain in the spruce soundboard, then views and 
methods do differ and always have done to some extent, and ultimately 
each maker or restorer who strives for the highest degree of 
perfection in the responsiveness and tone quality of his pianos makes 
certain judgements based on taste, sensitivity, acuteness of hearing, 
personal musicality etc. etc. and hopes to develop methods that will 
produce this elusive quality.

A long time ago asked a friend who has principal pianist with the 
Shanghai Symphony Orchestra what it was most that led him to prefer 
the Steinway, and his answer was that a Steinway "has bones".  I knew 
what he meant and I know now that "bones" (and I don't mean ribs!) is 
_one_ of the essential qualities of the piano tone that I seek out 
and aim to reproduce.  Without bones, other essential qualities of 
the modern piano sound that _I_ aim for cannot be properly developed.

Now my experience and taste suggest to me that the qualities I am 
looking for are closely connected to the state of compression of the 
soundboard.  I am at a disadvantage in not having had direct contact 
or heard recordings made with pianos whose soundboards are made by 
variations of the "RCS" method.  To say I am open-minded would be 
mildly hyperbolic, but I'd like to know where I can hear them 
on-line.  My mind opens and changes very promptly when I get evidence 
to dispel my illusions.

JD