Phillip Ford wrote: > > I keep reading posts by various people stating that the soundboard > gets 'stiffer' as downbearing is applied. But I have seen no > experimental evidence to support this supposition. Well I agree the soundboard does not get stiffer in its self. That's why I have using the phrase "apparent stiffness". When we pull the tension up on a string the wire becomes more resistant to deflection as if it were stiffer. But the steel in the wire is no more stiff than before. What is happening is that the wire when in tension can readily transfer any further loads to the plate and this greater structure makes the wire resist deflection. When the soundboard is pressed down by the down bearing it is no more stiff than before but it is now connected to a portion of the tension of the string plane and because it has crown it presses outward and receives further support from the case. When the vibrating strings meet the bride the impedance it reacts to is that of the soundboard, a portion of the string tension in the string plane and some of the mass and stiffness of the rim. Think of it this way: the bridge is sandwiched between two springs, on top is the down bearing and on the bottom is the crowned soundboard. John Hartman RPT John Hartman Pianos [link redacted at request of site owner - Jul 25, 2015] Rebuilding Steinway and Mason & Hamlin Grand Pianos Since 1979 Piano Technicians Journal Journal Illustrator/Contributing Editor [link redacted at request of site owner - Jul 25, 2015]
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