David Love wrote: > John: > > I don't know if you are rib crowning or compression crowning, but might > that difference be explained by changes that occur due to compression after > the board is installed? > I don't think the method of crowning will make a difference here. What compression are you talking about? If you are talking about the SB picking up moisture, yes that could make it stiffer. But my observations are made with the SB at the same moisture content (or very close) so there will not be any additional compression (this compression would happen with either a rib crowned board or a panel crowned board). I am talking about the difference in SB stiffness (resistance to load) between dry clamping into the case and gluing it in. I notice an increase in stiffness. I interpret this to mean that a soundboard receives additional support from being firmly attached to the case. Because I use wedges to pre stress the board before setting or adjusting bearing I can feel how stiff the board is. I suppose if you didn't use the wedges you may not notice this. The soundboard is like a stiffening spring, it gets firmer as you press it down. I notice the increased stiffness at the bottom of the pre stressing, the slack area at the top seems to remain fairly loose. I usually find I need to lift the plate up 2mm or more in the middle and bass. The treble remains pretty mush the same. This is fairly predictable and Steinway plates are easily adjusted (with the plate dowels not the plate bolts) before securing the plate down and stringing. 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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