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>>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.
>>. . . the laminated panel, with cross grain which is much less
>>prone to change dimension with hygroscopic variations, will result
>>in a panel which is more stable regarding tuning stability. After
>>having some experience with laminated panels, and after finding
>>that there is almost no shrinkage of the panel when dried down to
>>6% moisture content, I would doubt if CC boards could be made using
>>laminated panels, since to achieve any noticeable crown, one would
>>almost certainly have to crown the ribs.
>
>I think you're right that CC methods wouldn't work with a laminated
>panel. I also agree that a laminated panel seems superior to a
>solid panel for a host of reasons. From a performance standpoint,
>the only reason that I can think of to use a solid panel is that it
>might be better sonically.
I can't detect any difference. If I could, there would be no way I
would use a laminated panel.
> I can imagine that this might be true, but I can't imagine what
>the reasons would be. I suppose the only practical way to establish
>this is pianists ears. If they say that there's no discernible
>difference, or that the laminated panel sounds better, I see no
>reason to use a solid panel.
>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 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.
>>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. While some might see this as a disadvantage,
>>since 1/3 of the panel thickness is oriented with the ribs, I don't
>>see any problems associated with it. Certainly the laminated panel
>>is somewhat more flexible along the line of the long bridge, and
>>stiffer parallel to the ribs, but the long bridge if adequately
>>dimensioned will be more than capable of ensuring the whole
>>assembly maintains its togetherness. With a rib crowned board, the
>>most important job the panel has do is to ensure that air doesn't
>>leak past the ribs when they go up and down. The laminated panel
>>will do this without encouraging variations in crown as moisture
>>levels change.
>
>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.
> 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.
> Or perhaps it's not so much the absolute grain direction, but the
>grain direction relative to the orientation of the ribs. I've
>certainly seen many older pianos with various grain orientations.
>But they generally seem to have the panel grain nominally
>perpendicular (more or less) to the ribs. Perhaps things were set
>up in this way because they were using the ribs to help crown the
>board.
Most likely.
> 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.
> 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.
--
OVERS PIANOS - SYDNEY
Grand Piano Manufacturers
_______________________
Web http://overspianos.com.au
mailto:ron@overspianos.com.au
_______________________
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