Indeed I do ! These guys claim RIB crowning leads to curveacouse permanence !... and here I thought you needed an operation to fix that trick. I like the disadvantages bit.... really.... a sheet of paper on a ball.... :) Farrell wrote: > Hey Ric, maybe you'll enjoy this one more - it goes even further - > from the Bluthner web site: > > /At the beginning of piano making the soundboard consisted solely of a > thin wooden board, stiffened with bars glued on the underside and the > bridges on the upper side. Further development was derived from the > soundboard of a violin with its spherical crown. However the > soundboard of a violin is made of a thick piece of wood being shaped > by grinding, chipping and sanding into its final form./ > > / / > > /A piano soundboard is made from a thin board being bend by force into > this form. This method however produces disadvantages comparable to > those which one will experience when you try to put a sheet of paper > atop a ball./ > > /Studies made by Bluthner research and development department have > proven that tensions and compressions develop on the edges that are > inhomogeneous and not controllable. In contrast, the soundboard that > Bluthner has developed has a cylindrical curvature so that the tension > of the soundboard can be exactly defined. The ribs are planed to fit > the curvature needed and therefore the tension of the soundboard > remains intact over the decades. In fact, even under difficult > climatic conditions the curvature will remain in a constant form since > not only the rib structure will hold it in place but also the red > beech inner rim is preformed to the correct angle to receive and > retain the soundboard's curve tension. Because the soundboard is > pre-stressed in this fashion it can be fitted exactly and _remain > under curve tension permanently._ The bridge, of course, is adapted to > the tension and curvature of the soundboard in its optimum position. > This ensures that string vibrations in their full spectrum are > transferred to the soundboard. By utilizing the resonating surface, > the special design of the Bluthner soundboard generates tone > significantly better. / > > Ok, new terms now. "Curve tension" - any engineers out there? > I think you can read tension as <<stress>>. They seem to use the word thus over here. Clearly they are not pre-stretching the thing and expecting it to survive the dry central european winters. :) Looks to me like one on the rib crowned / beveled rim team. At least thats half way over in your camp ! Tho... if one first wanted to argue... one would mention that fully homogeneous and controllable stresses are not nearly the advantage as rib-crowned enthusiasts would have us believe. Especially when the cost is the reduction of internal compression so necessary to create that wonderfully CSB sound. Not that I can really pick sides mind you... I'm just a poor preachers kid from Montana :) > Look that up in your old Engineering 101 book. Cylindrical curvature? > The top of their inner rim in not more-or-less planar (and the few > that put a slight rise in the concave curved side doesn't count)? And > somehow the angled inner rim retains the soundboard's curve tension! > Also, how does one go about adapting a bridge to tension and > curvature? The curvature I can roll with, but the tension? Who/what is > pulling where? Or maybe they are just pulling our leg? > > Fun thoughts. > > Terry Farrell >
This PTG archive page provided courtesy of Moy Piano Service, LLC