>Ron, > >Is not it more or less a back post problem , that allows the >soundboard to be less stiff in there , is not one missing under the >killer zone ? > >Tell that because of the use I've seen of an metal apparatus to >reinforce the linkage there . > >Regards. > >Isaac OLEG Isaac, No, though the missing brace makes it worse. Bracing the belly bar does help some by stiffening the bar and keeping it from bleeding off soundboard energy quite so fast, but bracing rims doesn't stiffen soundboards. It just increases rim impedance. The fundamental problem is that compression crowned soundboards are often not stiff enough in the treble unless the panel is very thick. Diaphragmming the panel just aggravates the problem. Since the flat ribs resist crown formation, the crown and assembly stiffness is determined and limited by what any given panel has to give as it re-hydrates and expands. Using machine crowned ribs of appropriate dimension, therefor stiffness, makes the stiffness of the assembly much more controllable and dependably reproducible, as well as giving the capability of making the board stiffer or more flexible in different parts of the scale as required with a uniform thickness panel. And a relatively thin one at that. The killer octave always was a soundboard problem. Regards, Ron N
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