Virtual Ribs, A new crown support method

[David Ilvedson]

Hi Ric,

As I understand it...magnets opposing each other are aligned, one set in the bridge and one set along the beams under the bridge.   The soundboard is forced up?   Is is possible this would impair movement of the soundboard?   Are you drilling a hole in the bridge and inserting one of the magnets there?   Interesting experiment ...

David Ilvedson



----- Original message ----------------------------------------
From: Ric Brekne <ricbrek@broadpark.no>
To: pianotech <pianotech@ptg.org>
Received: Tue, 12 Apr 2005 11:21:28 +0100
Subject: Virtual Ribs, A new crown support method


>Hi David

>I do not believe I said this was better then any other method.  I did 
>mention the ability to seperate concerns of mass and stiffness. As far 
>as overstressing the panel is concerned, (I suppose you are refering to 
>the compression crowning discussion)  I simply do not recognize the 
>validity of many of the claims made on this list in that regard and 
>hence do not see any definition of <<overstressing the panel>> in that 
>context that needs to be worried about. And it seems a very large 
>proportion of the piano manufacturing industry is in aggreement on that 
>point. On the contrary, it seems more and more apparent to me that 
>compression soundboards do indeed create a different sound that can not 
>be achieved otherwise. One can use opposing  magnets to strengthen any 
>area of a compression panel one wants, or one can simply create an 
>essentially rib crowned panel that allows more freedom relative to mass 
>and stiffness concerns.  Or... one can get all creative and see what 
>else one can come up with. 

>A few weeks back on a beater I have experimented with I changed both the 
>pitch and increased sustain characteristics in the mid treble area just 
>by alligning three such magnet pairs so that they were seperated by a 5 
>mm gap. Turning them up to 3 mm gap further raised pitch but seemed to 
>thin out the sound a bit despite relatively long sustain.  It seems to 
>me there is lots of room for experimentation along these lines.

>Cheers
>RicB




>David Love wrote:

>Why would this be better than simply creating a rib crowned and
>supported panel that can be compressed to the requisite stiffness
>through the use of downbearing without overstressing the panel?

>David Love


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