---------------------- multipart/alternative attachment Terry Very well said. You took the words out of my mouth. I don't think any one is saying the a rib crowned board sounds better than a C.C. Board. I believe Del ,Both Rons , & probably You & now me have gone on record as saying so. What has been said is that the dependabliltiy of maintaining crown & mechanical impedance qualitys are more dependable over time & less subject to failure. We all have our biasis though. But Consider this Terry you are right ,most small shop rib crowners I Know Dry down to a range 5.5 to 6.5.% E.M.C. So some panel compression is still utilized but crown not dependent on compression that much to form crown or maintain it & even in the driest invirons the crown won't shrink out of exisistence. This is dry. This is equal to an environment of 85 or 90 degrees & 25 or 30% R.h. Now any body who's lived thru a dry summer knows this is dry. Many C..C.Boards are dried to 4% to 4.5%(or less) Which is more like 100 Degrees plus 15% to 20% R. H. To me this Nevada desert dry. This is why the damage to panels In C. C. thru compression will be greater given huge swings in climate change. They are more reactive because of their inherent panel dryness. The other problem with C. C crowning is that it has a very narrow range of parameters in order to be successful & live long. I think the small shop rebuilder has way more control over the EMC of his/her panels prior to ribbing than most mass produced facilities. If I wanted to build a board this way I would be absolutely sure that the board was at 4.5%emc.No less & no more when the board has it's ribs pressed on. All that being said I've heard many fine examples of both in older pianos. Older rib crowned board are out there but far and few between. I've heard many newer versions I like equally well. I have a 1929 Steinwya B Calif. piano. This C.C board has text book crown & bearing. I have documented this when it was apart. I rebuilt a 1960 L from Fresno same thing. There are no cracks in either board & the tone just floats. Two small examples but there are many more. I've also heard Older boards with little or no crown or bearing that are magic. ??? The reason this can be so is that the mechanical impedance of the system is working with that scale,board shape, crown & bearing for some reason. I find this especially plausible In old As, 2 & 3. I have a 1905 gigantic Ludwig upright that sings like an soprano with endless air thru out the scale. It has taller than wide ribs and plenty of them. The board is not cracked up. I do not know it's history but it's stunning. Viva la difference. When you hear something that's working ask why ,marvel & observe the ribbing , it's height/width, no. of ribs etc this the way we learn from the folks that have gone before. I'm grateful to them all. what a great journey. Blessings--- Dale IfI believe it would be accurate to say that there is a continuum between the two extremes of 100% compression crowning and 100% rib crowning - it is not as if there are two distinct schools of thought on the subject. Some lower-end small pianos have been manufactured with super-dry panels, flat ribs, with the ribs glued to the panel on a flat surface - that process represents one end of the spectrum (actually, I think many, many, if not most, vertical pianos have soundboards manufactured like that). The other end of the spectrum would be no panel drying at all, and ribs cut/formed to the desired radius. I am not aware of anyone that is at that end of the spectrum. All the soundboard builders that I am aware of who build "rib crowned" soundboard utilize at least some small degree of panel drying prior to gluing ribs to the panel. I believe most soundboard manufacturers build hybrid soundboards - that is the ribs will have some radius cut/formed into them (often the 60-foot radius one hears of so often) and the panel will receive a fair bit of drying prior to ribbing. Steinway even modifies the 100% compression crowning process by drying the panel, using flat ribs, but gluing them to the panel in radiused cauls. Most builders that utilize some pre-formed radii to their ribs will glue clamp the ribs to the panel using a matching radii caul. I think if you looked at all the soundboard builders in the world, you will see that continuum in the building process from one extreme to the other (or nearly so). Terry Farrell ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/0e/13/c3/54/attachment.htm ---------------------- multipart/alternative attachment--
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