Scale design question -- Tuning Stability

Overs Pianos sec@overspianos.com.au
Sat, 28 Apr 2001 09:37:59 +1000


Del, Michael and list,

>Michael Jorgensen wrote
>on April 04, 2001
>
>>  To Del Fandrich, Dampp Chaser, and Other
>>        How much consideration is given to tuning stability in
>  > scale/board/bridge/rib design?

Unfortunately, most manufacturers speaking length scales are based on 
what's gone before. As Del said yesterday in his excellent post on 
the Baldwin dilemma, you don't stay afloat producing the same old 
outdated designs.

>  > Much focus is on even tone and smooth
>  > temperament over the break.

But not enough in many cases. Many even high class pianos have poorly 
laid out string scales which result in poorly match sound board 
impedance across the break.

>  > but  how about making the low
>  > tenor so it changes more equally with the rest of the piano in a weather
>  > change?  How possible is that?  How much sacrifice would be needed?

Think 'percentage of breaking strain' (%BST) here. It is possible to 
design scales which are very much better in %BST across the break 
than what is typical, but there must still be some deviation at the 
transition (which hopefully is not on the long bridge - since that 
does not work) from trichord plain wire to bichord cover.

Del wrote;

>We are not going to resolve the tuning stability problems until we get over
>our irrational obsession with 'solid-spruce' soundboards and develop some
>really good laminated soundboards -- work that is overdue by some decades
>now.

An interesting comment Del. The obsession you mention has probably 
come about since most pianos with laminated panels have been poor 
instruments (in both design and workmanship). We are using laminated 
panels in our first Overs - Steinbach 225 grand pianos (the piano we 
are bringing to Reno will have a modified laminated panel). I too 
believe that the laminated panel will improve tuning stability, but a 
laminated board needs to treated somewhat differently, the solid 
panel cannot be just substituted with a laminated panel, since I 
suspect that the laminated panel is much stiffer than the solid. It's 
early days, but I like the performance we're getting with the 
laminated panel.

>  > Tuning instability could kill the acoustic piano.

Del replied;

>It is certainly going to help. But this knowledge has never rallied our
>industry in the past.


Agreed Del, but it's about time 'this knowledge' did cause a rally of 
some sort.

I have been working on this problem for some time, and our next 
production grand piano (which has now grown in length 15 cm from 170 
to 185) will have a very different scale with considerably less %BST 
deviation, and better tuning stability as a result.

Ron O
-- 

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Website:  http://www.overspianos.com.au
Email:      mailto:ron@overspianos.com.au
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