Overs laminated soundboard

[Ron Nossaman]

>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.

I don't see why there would be with a decent modern glue, competently used. 
Plywood comes apart too when it's poorly put together.


>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.

Sure they could, and each buyer would want a different lamination thickness 
configuration and relative grain angles between laminations.


 >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.

No one has said the panel isn't doing anything. In a compression (panel) 
crowned board, it supplies all the crown and stiffness. In a rib crowned 
but panel supported board, it supports a large portion of the crown and 
stiffness. In a rib crowned and rib supported board, it supplies nearly 
none of the crown, but still supplies stiffness along the grain - as do do 
the other two types mentioned. The panel ties the ribs together and helps 
move the assembly as a unit. For that, there needs to be some stiffness to 
it in a specific direction, even if it impedes movement of the bass bridge.


>  I think you're right that these questions will still be asked in time to 
> come.

I agree.


>Part of the reason for this is that some people have to see for themselves 
>in order to be convinced.

And a good portion will never be convinced no matter what they see or hear, 
so the questioning will continue. As it should, I think, if not for that 
specific reason.


>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 exerc!
>ised?  So, the results (if you can call them that) are useless.

Exactly, and even when someone tries to conscientiously and as objectively 
as possible preserve and pass on all the information, experimentation, 
logic, and details of the reasoning, experience, and controls that went 
into the investigation, it is for the most part ignored or dismissed as 
irrelevant, unproven, contrary to what is commonly known, believed, and 
practiced, or non-intuitive and therefore mistaken.


>If you have any interest, then you have no choice but to start from 
>scratch.  So, our industry has to keep reinventing the wheel.

Yes, starting with how many sides it ought to have. An old BC cartoon had 
Thor extolling the virtues of the triangular wheel over the square one 
because it eliminated one bump per revolution. I'm sure I've tuned the 
piano that line of reasoning produced.

Ron N