>I remember Ron N. mentioning that he gets a general idea of what the load >on the board will be once strung. I'm assuming he now has an idea how >tall to make the ribs to support this load. Yes, that's the idea. Since I'm not expecting much, if any support from panel compression, I want some idea what the ribs will support. >What are the consequences of going a step further? Will this make the >board too stiff? It can. A more flexible board will tend to be generally louder, with shorter sustain. A stiffer board will tend to be not as loud, with longer sustain. > Will the bass suffer? Yes. If there is to be any hope of getting a fundamental out of the low bass, the board needs to be flexible down there, and the back scale needs to be long, and the core wire needs to not be the diameter of an 8d nail. At the same time, the treble needs to be stiff or you will get the percussive attack and short sustain of the "killer octave" through the last two octaves or so. Stiffness requirements are widely different from one end of the scale to the other. >I think I also remember Del mentioning something about a board giving too >much of a percussive sound and not as much string sound. Is this with a >board that is too stiff? Probably too flexible. >How does the thickness of the board relate to how much load it can support? It depends on the crowning method. A compression crowned board will be stiffer with a thicker panel, and support comparatively more load than a compression crowned board with a thinner panel. With a rib crowned board, assuming it is really rib supported and not just a compression crowned board with machine crowned ribs, the panel thickness makes much less difference. With a rib crowned, rib supported board, there is no need for a thick panel if the rim is solid. >And in relation to the rib thickness? Again, it depends on the crowning method. Compression crowned boards tend to have ribs wider than they are deep, because they start out flat and the panel expansion has to bend them to form crown. Rib crowned and supported boards will have ribs less wide, and deeper, regardless of panel thickness. Ribs get stiffer in proportion to their width, and to the cube of their height (and inversely to the cube of their length), so a little bit of rib height makes them a lot stiffer. >I'm sure all these things are interrelated. What are the trade-offs? Those are some of them. >Next, I'm sure the size of the board is a factor. A smaller piano will >have more support from the rim, because the there is more rim per area of >board. Yet another factor to consider, aye? Absolutely. Soundboards, contrary to manufacturers' marketing literature bragging about how their soundboards have more area than their competitors', are for the most part already too big. Redesigns I do typically lose something around 20% of the existing active soundboard area, depending on what I started with. >How does one judge or weigh the trade-offs? There are so many variables. A bunch of variables, the most critical of them not the ones we have always been taught were all important. One can either put in a couple of hundred soundboards, making incremental-to-major changes in virtually everything until he works out a set of priorities and effects of design features, or he can do what I did and start rethinking what I thought I knew against the good fundamental science and physics based advice and guidelines of someone who did do the basic R&D from scratch. That would be Del. >There's no real point here to my questions. I am always trying to learn >more about my trade. And who else do I learn from other than the folks >who do this every day? > >Mike Bratcher Every day's a new day for all of us isn't it? There's always something to learn - and heal up from. Ron N
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