Overs laminated soundboard

[Delwin D Fandrich]

----- Original Message ----- 
From: "Phillip Ford" <fordpiano@earthlink.net>
To: <pianotech@ptg.org>
Sent: August 23, 2003 12:01 AM
Subject: Re: Overs laminated soundboard


> >
> >>There are several compelling reasons why I believe the laminated
> >>panel is superior to the solid version.....cracks in a laminated
> >>panel are almost unheard of.
> >>
> >>So 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.

That would depend entirely on the grain orientation of the various lamiae.
If they were all in line it would still be a laminated panel and it would
be possibe to make a compression-crowned soundboard system with it. Of
course, it would still be subject to the same structural problems a solid
panel would suffer.



> >
> >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 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.  I wouldn't think the difference in
> >price would be a consideration for a high end maker.

I have been on record for a number of years on this issue. In my experience
pianos using laminated panels can, and have, outperformed otherwise
identical pianos using solid panels. I've written a number of posts on this
issue.


>
> >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.  Once
> >again, the only reason that I can imagine is a sonic one.

Personally, I think this is a holdover from the compression-crowning
technology. We have been deviating from this convention for many years with
solid panels.

In general (and taken to its extremes, but with all other factors remaining
equal) a soundboard panel with a grain angle closer to perpendicular to the
bellyrail will have a better treble response but a poorer bass response.
One with a grain angle running closer to parallel to the bellyrail will
have a poorer treble response but a better bass response. Consider the
effect of grain angle on the stiffness of the soundboard system at the
bridge(s).


>
> >Perhaps
> >the board behavior is influenced in some significant way by the
> >panel grain direction.  Or perhaps it's not so much the absolute
> >grain direction, but the grain direction relative to the orientation
> >of the ribs.

It is both. I can't remember the last time I designed a soundboard with the
ribs running perpendicular to the soundboard grain angle. Consider the
effect of each--separately and in combination--on the mobility of the
bridge(s).


>
> >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.

I believe this to be the case.

Del