>>>After much consideration, I am now of the view that I probably won't >>>ever use a solid sound board panel.... I am referring to carefully built >>>laminated panels, where each laminate is constructed as if it were to be >>>a first quality solid sound board panel, but 1/3 the nominal thickness, >>>ie. properly quartered boards shot and joined properly with no air gaps. >>>Three of these 2.5 mm thick panels make up one laminated panel (we sand >>>the middle laminate to 2.5 and the outers to 2.8 - this allows for some >>>final sanding after they are glued together). >> >>How did you decide on 3 laminations, rather than, say, 5? > >Since we are sawing the laminations then sanding them to size, there is >already considerable waste in the process of converting the basic material >into thicknesses suitable for laminating. Furthermore, it seems to me that >the '5 lamination school' of laminated panel manufacturers are using the >top and bottom laminates (which are typically a 1mm laminates, which after >finish sanding are approximately 0.5 mm thick) to disguise the more >ordinary material which they use for the internal laminates, where they >can't be seen. I would prefer to use three laminates only because it is >less wasteful of materials and labour, and the result is every bit as >good, probably better since we aren't using trash wood anywhere in the >panel, and it is quarter cut. Some of the so-called quarter cut material >which is used in both laminated and solid panels leaves much to be desired >much of the time. I see. Good reasons. I'm not a plywood or laminated panel expert by any means. But in ordinary plywood they try for very thin layers and lots of them, presumably to prevent much movement of the panel even with changing humidity. And I thought part of the reason for preventing movement (aside from dimensional stability) was to prevent breaking down the glue joints. I wonder if there is any long term danger to the glue joints with 3 layers 2.5 mm each. >>....Some low end manufacturers might prefer solid panels, since I imagine >>they might be easier and cheaper to make. > >My recent experience with a manufacturer who has changed from mostly >laminated panels to solid tends leads me to think that poorly set up >pianos with solid panels could be even worse than poorly set up pianos >with laminated panels. I would think that this would be true. Why did they change from laminated to solid? Marketing? >> I wouldn't think the difference in price would be a consideration for >> a high end maker. > >True, but the commercial maker would probably slice the laminates rather >than sawing them, giving them a significant competitive advantage. Perhaps if laminated panels in pianos became common enough suppliers would start making them in quantity. One could buy a laminated panel just as one can currently buy a solid panel. >>>We are running the top and bottom laminates in the same direction as for >>>a traditional solid panel, ie. along the line of the long bridge, with >>>the middle laminate at 90 degrees and parallel to the sound board ribs. ... >> >>This topic of grain orientation has been discussed before. It's not >>clear to me that there is any inherent advantage in orienting the grain >>along the bridge. I can't think of a structural reason. > >Me either, but since we're already building a very different sound board >which will likely alienate many who won't accept anything which is >different from the way it's always been, I would prefer to orient the top >and bottom laminates to make it look more like the traditional way even if >it is not. If we were to find that it is better to run the grain the other >way then we would certainly do it. But until then - tradition nearly rules. Sound reasoning. >> Once again, the only reason that I can imagine is a sonic >> one. Perhaps the board behavior is influenced in some significant way >> by the panel grain direction. > >I doubt that the panel would have much of an influence on the tone. I >would consider the rib and bridge section modulus to be much more important. I don't know. I hear various things: Grain one way improves bass response. Grain another way improves treble response. Crowning the panel and preloading it improves treble response. Thicker panel has more punch. Thinner panel has more sustain. Floating the panel or undercutting it in the bass improves bass response. Leaving the panel thicker at the treble end improves treble response. Etc. The panel is apparently doing something. In spite of the many explanations I hear I don't think I really understand what it's doing. But, if the ribs and bridge are designed to take all the string load, and all the panel is doing is filling in the gaps between the ribs and moving air, then it could be 1 mm thick with any grain orientation. I haven't yet heard anyone advocating that. >>... Perhaps this layout is important for the vibrational characteristics >>of the soundboard. I don't know. > >I doubt it, but I suspect that no-one can be sure. No. Not without extensive testing. >> Here also, I suppose the practical way to establish this would be >> listening tests. > >Indeed, but as always, once we've listened the hard part is knowing what >elements have been critically responsible for the perceived tone being >what it is alleged to be. And contrary to the rhetoric of certain closed >minds in our industry, someone will still be asking these same questions >in fifty years time. > >Best, >Ron O. Yes. This is always the problem with changing things. Especially on something with so many variables, like a piano, on which the variables are difficult to control. Because of the materials and building methods involved it's virtually impossible to hold all parameters constant except the one that you want to test. I think you're right that these questions will still be asked in time to come. Part of the reason for this is that some people have to see for themselves in order to be convinced. But part of the reason is that when these things are investigated there is no significant documentation made available so that in future people will know what has been tried and what the results were. Often, the only information that we have is anecdotal. Oh yes, I heard that such and such company tried laminated soundboards and they were a failure. Who knows if this is true or not? And if it is true who knows what kind of experiment they did and what kind of controls were exercised? So, the results (if you can call them that) are useless. If you have any interest, then you have no choice but to start from scratch. So, our industry has to keep reinventing the wheel. Regards, Phil Ford Phillip Ford Piano Service & Restoration 1777 Yosemite Ave - 130 San Francisco, CA 94124
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