As diaphragmizing soundboards has come up I will throw out my novice thoughts: Why is it that the bass/lo-tenor area of the board is always diaphragmized? Why not the treble? Seems to me that for an radius crowned board that has very little compression, it is the ribs that respond/restore the board that is displaced by string/hammer energy and a more massive board should tend to bring out the fundamental more efficiently - conversely a less massive diaphragmized part of the board in the treble would be less massive and tend to bring out these higher frequencies??? Thanks for reading. Gene Ron: I've never quite understood why you (and others who do designs similar to you) *don't* fully diaphragmize the panel. I understand why one wouldn't necessarily thin the panel in a compression crowned board as it reduces the strength in the panel needed to form and maintain crown under compression. But in your case you don't need that. In addition, you taper the ribs as they approach the perimeter--in fact by a good amount starting 1/3 into the length of the rib, you've reduced the overall mobility of the board by installing a large cut-off bar, increased the relative stiffness of the rib scale, increased the grain angle to add additional stiffness. So why wouldn't you do a full diaphragmizing of the panel in this type of design in order to create the greatest amount of mobility for the panel that remains? You've already accounted for stiffness by the rib scale alone as if the panel isn't there (or so you've stated in the past). It doesn't make sense to me. David Love www.davidlovepianos.com > If I'm using tight grain Sitka spruce I will want to thin the entire > panel to 8 ish mm and the thin it at the rib scoops/perimeter and > further into the panel. I haven't used anything but a constant thickness panel for some time. Ron N
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