I don't believe that bearing and crown are required to drive the board. The coupling of the strings to the bridge is enough to drive the board. The problem I have with zero bearing (if what you say about the Stuart pianos is true) is that it seems to miss an important function of downbearing which is to control impedance and to load some potential energy into the board by flexing it downward. The function of crown, then, is to create a domelike shape that can be flexed downward much like loading a spring. The unloaded spring has less potential energy and lower impedance characteristics. The key to this (simply stated) is to create a system that is crowned adequately and made light enough that the loading of the system with potential energy via the setting of downbearing also pushes the impedance up to the targeted level. The pairing of those two processes is critical. If the board is designed with the idea of no downbearing, then it can't achieve the required impedance characteristics by loading. The board will have to be built heavier. Because there is no downbearing, the soundboard spring will be devoid of loading with potential energy and the tone will be relatively linear and lifeless. At least that's how I look at it. David Love www.davidlovepianos.com I have heard that agraffe bridge systems like the Stuart is designed to be used at "zero bearing" ( I believe that Stuart claims to be such, if I am not mistaken). But I have never understood why, if all else about a soundboard assembly is equal in design and construction, that this would be the case. It seems to me like they would have more or less the same requirements of bearing and crown to drive the board. Will Truitt -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20130108/7270694a/attachment.htm>
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