NEWS FLASH! "Conover clobbers Steinway !"

[Michael Spalding]

Ric,

I've never understood the importance of sound travelling through the
soundboard parallel to the grain and across the grain.  When we "hear" a
piano, we're sensing air pressure differences, which are created by the
diaphragmatic movements of the board.  Wogram states clearly in the
excerpts you provided, that the ribs are there to equalize the stiffness of
the board across and parallel to the grain, to optimise the diaphragmatic
response.  He says nothing about the speed of sound transmission throught
the wood, at least in the excerpts provided.  Where does this idea come
from?

Your online dictionary gives transmission speed as ONE EXAMPLE of
anisotropism, but Wogram is specifically referring to bending stiffness,
not transmission speed, as the anisotropic property being influenced by the
ribs.

I was watching Andre Bolduc's taped class on soundboard replacement the
other day, and he talked about the treble "reflector".  On S&S soundboards,
this strip of maple is attached to the beveled end grain of the soundboard
at the high treble end, according to Andre it's to keep the sound from
leaking out of the end grain.  Huh??  Where does this idea come from? 

Mike


> [Original Message]
> From: Ric Brekne <ricbrek@broadpark.no>
> To: pianotech <pianotech@ptg.org>
> Date: 2/4/2006 7:05:02 AM
> Subject: NEWS FLASH! "Conover clobbers Steinway !"
>
> Hi Dale
>
> Prompts me to ask a bit about an idea being thrown around in an off list 
> dialoug I am having with a couple folks. The idea is not mine but it 
> sounds intriguing.  Let me throw this at you (and whomever else might be 
> interested to comment). I'll let the fellow who threw this at me speak 
> up for him/her self if they so choose.
>
> The primary acoustic function of the ribs is to transfer sound cross 
> grain more or less as fast as it otherwise buzzes along the grain.  What 
> if we could make a soundboard with enough crown support perpendicular to 
> the bridge without support  from the ribs (or nearly as much as we use 
> in todays instruments) ?
>
> The idea that strikes me as being able to perhaps do exactly this is to 
> allign the grain perpendicular to the bridge, and construct a 
> pre-crowned soundboard panel of several laminants, all with grain going 
> the same direction. With the grain going perpendicular to the bridge and 
> what crown support the unribbed soundboard would have, cross grain 
> ribbing would be able to do their acoustic job and provide a bit of 
> extra support to the curvature of the wood while being of much smaller 
> dimensions.  In addition... the bridge itself would function like the 
> ribs in speeding sound cross grain.  It might be a way of approaching 
> the different requirements of the bass and high treble areas.
>
> Cheers
> RicB
>
>
> Ric
>
> Well .....When the return on investment is marginal, many  alterations 
> do not pay.  I am a business man too.  However they  both got the usual 
> rib crowned treatment with taller narrower spruce ribs  instead of the 
> original sugar pine rib, plus some panel tapering.  I  have to remind 
> myself that one of the biggest alterations you can make is to use  & 
> crown spruce ribs to achieve bearing load support.  This makes a  
> tremendous improvement even though it may not solve all the anomalies 
> many of us  on list do not care for.  The top 3 treble sections hammer 
> strike line , was  VERY  fussy &  Closely dialing that in made a 
> tremendous  difference.....as it always does.
>
> Thanks
> Dale
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