Untapered Soundboard Ribs

[Erwinspiano@AOL.COM]

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In a message dated 7/18/2002 3:57:22 AM Pacific Daylight Time, 
mfarrel2@tampabay.rr.com writes:


> Subj:Untapered Soundboard Ribs 
> Date:7/18/2002 3:57:22 AM Pacific Daylight Time
> From:<A HREF="mailto:mfarrel2@tampabay.rr.com">mfarrel2@tampabay.rr.com</A>
> Reply-to:<A HREF="mailto:pianotech@ptg.org">pianotech@ptg.org</A>
> To:<A HREF="mailto:pianotech@ptg.org">pianotech@ptg.org</A>
> Sent from the Internet 
> 
> 
> Terry F. wrote
> The Mehlin grand I worked on the other day had untapered ribs on its 
> soundboard. Ribs on other pianos are somewhat abruptly tapered near the 
> ends. Is that so the panel will tend to move as one unit and flex around 
> the perimeter - somewhat like a speaker cone might move with its firm cone 
> and soft surround material that connects the cone to the basket (I kinda 
> don't think this is really a good analogy). It would seem to me that 
> untapered ribs are quite a departure from "the proper way to build a 
> soundboard".
> >>>>>Is there a proper way? well at least many principles with Merit and 
> testing. Hey you know how opinions are.
>           The speaker analagy is  gives the general idea.

>>>>>>>I believe that"s the concept but in practice how much tapering is up 
for grabs. Remember the George Fredrick Stein grand piano I posted about a 
while back? Same deal as the Mehlin. Zip taper nice sound. Funny you should 
bring this up As I've been thinking about this lately too.
     One thought is I think too much thinning is overrated. Second though is 
that a rib with a cut radius does taper from the middle out any way so just 
feather that off into the notch but not as severe as the old style. I,m doing 
a Baldwin right now that I'm trying this on. On the long ribs I think this is 
not a huge risk but up along the belly rail where traditionally the cutouts 
are mighty severe and intentional leads me to believe this is more critical 
especially as the bridge gets closer to the belly rail, know what I mean? It 
would seem that if the killer octave lacks stiffness in that area any way why 
thin it out? This is my question.
    I'd like to hear other opinions as well.
>>>>>>>>>Dale Erwin>>>>>>>>>>>

> 
> If soundboards vibrate their various frequencies in small random 
> (seemingly) areas of the board, why do we taper ribs like we do (the abrupt 
> taper near the end). Why not an even taper along the entire rib? Or no 
> taper?
> 
> The piano seemed to sound OK, but it was so old and worn that it was hard 
> to get a real good feel for it.
> 
> Any thoughts on untapered ribs - or tapering in general?
> 
> Terry Farrell
> 


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