> -----Original Message----- > From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]On > Behalf Of Phillip Ford > Sent: February 03, 2004 1:27 PM > To: pianotech@ptg.org > Subject: RE: Soundboard stiffening > > > > > >But not all springs are linear. Some are non-linear by design. > > That's true. But if I was trying to design a non-linear spring my first > choice would not be an essentially flat plate with ribs attached to it. Nor would it be mine. But that is not what we set out to design. We set out to design a piano soundboard. It just happens (at least in one case) to act like a non-linear spring. > > > You say that the deflections were not linear. Were they incrementally > decreasing for unit increases in load? As best as I can recall the amount of deflection was greater per increment at the beginning of the loading. With each increase in weight the board went flatter, but not by as much as with the previous increment. The biggest change in the amount of deflection came at the beginning. Toward the end it was pretty difficult to measure accurately. On reflection I suspect this was because the initial load support came entirely from compression within the soundboard panel while the ribs (though lightly crowned they were also moderately bent as in a compression-crowned soundboard system) were actually working to straighten the panel. Once the ribs reached their neutral configuration they began helping the compressed panel in supporting the load rather than fighting it, hence increasing the spring rate of the system. > > I thought your > position was that > there is essentially no difference in behavior or performance > between an RC > and a CC board. > > Phil Ford Not quite. It is my position that soundboard systems of both types can be made to sound essentially the same. At least initially. Their behavior and performance may well be different, especially as time goes by. Del
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