This is a multi-part message in MIME format. ---------------------- multipart/mixed attachment Del, Thanks for your explanation of soundboard impedance. In your other posting you wrote as follows; [ "The soundboard system will be more flexible if it does not have a string plane bearing against it. It will be stiffer if it does." and "The whole idea of loading the soundboard with string bearing is to make it stiffer (or "springier")." and then in a later message "Assuming, of course, that its string scaling, its soundboard and rib system and its supporting structure (soundboard liners, back assembly, etc.) is otherwise relatively conventional." ] If stiffness was designed into the soundboard in the first place would there be a need for string pressure? Here is a picture of the cross section of the soundboard that goes with this pressure bar (image also attached) system. As you can see it IS unconventional. The soundboard is double skinned, the outer panels being only 2mm thick. The overall thickness of the board is 15mm. The ribs are 23mm X 11mm placed 33mm apart. Because of the double skin, this board is very stiff, and very light. It is also my intuitive guess that this soundboard would be fairly immune to humidity changes - the theory being that, I suppose, the less material there is, the less moisture it can absorb or release and therefore the less it will tend to "heave". Sorry I don't have higher resolution pictures, but I am only a Tuner and can't afford such fancy gizmos to provide such. You see, I am just trying to figure out why after 300 years of piano construction, the problem of the killer octave and soundboard failure has not yet been solved. Make the soundboard with the desired impedance built into it before anything else, then use a system of string to bridge contact that doesn't rely on downbearing and hey presto.......no additional stress on the soundboard, no killer octave......but I suppose it is more complicated than that! If a picture paints a thousand words then a phone call must be worth a million e-mails. ---------------------- multipart/mixed attachment A non-text attachment was scrubbed... Name: Bridge.jpg Type: image/jpeg Size: 32823 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/0e/b7/41/4e/Bridge.jpg ---------------------- multipart/mixed attachment A non-text attachment was scrubbed... Name: Soundboard section.jpg Type: image/jpeg Size: 29098 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/99/12/32/6a/Soundboardsection.jpg ---------------------- multipart/mixed attachment--
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