<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; =
charset=US-ASCII">
<META content="MSHTML 6.00.2900.2668" name=GENERATOR></HEAD>
<BODY id=role_body style="FONT-SIZE: 10pt; COLOR: #000000; =
FONT-FAMILY: Arial"
bottomMargin=7 leftMargin=7 topMargin=7 rightMargin=7>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 =
size=3>Dale,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 =
size=3></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 size=3>1) I'd rather have the =
mass in the
bridge and the ribs than have it all spread out in the panel itself. =
(Think
about it some to see the ramifications of this.) </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 =
size=3></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 size=3>How much mass is enough =
is dependent
on the scaling. High tension scales obviously need both more mass and =
more
stiffness so you can use a panel that is a bit thicker in larger concert =
pianos
(but I still think anything over 8 mm is probably too much). Lower =
tension
scales need less of both. </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 =
size=3></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 size=3>2) Yes I mean thinner. =
The thinner
boards do seem to give up faster. There is more unit force in =
compression. I've
measured diaphragmed soundboards that were more like 4 mm and 5 mm =
around the
parameter (which is, I think, pretty close to Steinway's specification =
for
diaphragmed soundboards) and these are the boards that seem to give up =
the
fastest in extreme climates. </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 =
size=3></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 size=3>3) Since you are not =
depending on
internal compression to form and/or hold system crown you can treat the
soundboard panel as a non-structural member. This means you can vary its =
thickness to suit your perception of what the soundboard system need in =
terms of
mass (and stiffness in the treble where the bridge's proximity to the =
bellyrail
extension becomes an issue) and not worry about how thick it needs to be =
to form
and/or hold crown.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 =
size=3></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=078402705-24062005><FONT
face="Comic Sans MS" color=#000080 size=3>Del</FONT></SPAN><SPAN
class=078402705-24062005> </SPAN></DIV>
<DIV> </DIV>
<DIV><FONT face="Comic Sans MS" color=#000080 =
size=3></FONT> </DIV>
<DIV> </DIV>
<DIV><BR></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000080 2px =
solid; MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> pianotech-bounces@ptg.org
[mailto:pianotech-bounces@ptg.org] <B>On Behalf Of
</B>Erwinspiano@aol.com<BR><B>Sent:</B> June 23, 2005 7:44 =
AM<BR><B>To:</B>
pianotech@ptg.org<BR><B>Subject:</B> Re: Rib Crowned Hamburgs
?<BR></FONT><BR></DIV>
<DIV></DIV><FONT id=role_document face=Arial color=#000000 =
size=2>
<DIV> Del</DIV>
<DIV> Thanks for the perspective but what a bout an
appropriate amount of mass in this area adding to the impedance =
qualities? I
realize the importance of rib stiffness for this purpose but....how =
much mass
is too much or not enough? Too much thickness in the =
treble can
give a stingy sound & too thin sometimes a a sound not dark =
enough
for my liking</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT
style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 =
size=2>
<DIV dir=ltr align=left><FONT face="Comic Sans MS" =
color=#000080
size=3><SPAN class=343060314-23062005>Dale,</SPAN></FONT></DIV>
<DIV dir=ltr align=left><FONT face="Comic Sans MS" =
color=#000080
size=3><SPAN class=343060314-23062005></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face="Comic Sans MS" =
color=#000080
size=3><SPAN class=343060314-23062005>This is true only if the =
soundboard
assembly is compression-crowned where the thickness of the board is
necessary to support crown over the years. <STRONG>It<U>'s why =
diaphragmed
soundboards collapse more rapidly than do thicker
boards.</U></STRONG></FONT></FONT></DIV></BLOCKQUOTE>
<DIV><STRONG> Perhaps I'm misunderstanding your point =
here. Do you
mean thinner, as the compression load a on a thinner board would give =
up
sooner. Also most diaphramized bords are 8 mm or less around the
perimeter</STRONG></DIV>
<DIV align=left><FONT face="Comic Sans MS" color=#000080
size=3></FONT></SPAN> </DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT
style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 =
size=2>
<DIV dir=ltr align=left><FONT face="Comic Sans MS" =
color=#000080
size=3><SPAN class=343060314-23062005></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face="Comic Sans MS" =
color=#000080
size=3><SPAN class=343060314-23062005>If the soundboard is =
crowned using
curved ribs the bulk of the crown support comes from the rib and the =
panel
functions more as a non-structural diaphragm. <STRONG><U><EM>In this =
system
the thickness of the soundboard is chosen based more on</EM> <FONT
size=4>(acoustical needs</FONT> <FONT size=4>)</FONT><EM>and =
less on
structural requirements and 8 mm is quite =
adequate.</EM></U></STRONG>
</FONT></FONT></DIV></BLOCKQUOTE>
<DIV><FONT face="Comic Sans MS" color=#000080 =
size=3></FONT> </DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid">
<DIV dir=ltr align=left><FONT style="BACKGROUND-COLOR: =
transparent"
face=Arial color=#000000 size=2><FONT face="Comic Sans MS" =
color=#000080
size=3><STRONG>would you elaborate on
this</STRONG></FONT></FONT></DIV></BLOCKQUOTE>
<DIV><FONT face="Comic Sans MS" color=#000080 =
size=3></FONT> </DIV>
<DIV><FONT face="Comic Sans MS" color=#000080 =
size=3></FONT> </DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid">
<DIV dir=ltr align=left><FONT style="BACKGROUND-COLOR: =
transparent"
face=Arial color=#000000 size=2><FONT face="Comic Sans MS" =
color=#000080
size=3>This is especially true if a reasonable cutoff bar and a =
fish are
used.</FONT></FONT></DIV></BLOCKQUOTE>
<DIV> <STRONG><FONT size=3>Yes I see this makes sense. Less =
area is
automatically made stiffer</FONT></STRONG></DIV>
<DIV><STRONG><FONT size=3> Thanks</FONT></STRONG></DIV>
<DIV><STRONG><FONT size=3> =
Dale</FONT></STRONG></DIV>
<DIV></DIV>
<DIV align=left><FONT face="Comic Sans MS" color=#000080
size=3></FONT></SPAN> </DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px =
solid"><FONT
style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 =
size=2>
<DIV dir=ltr align=left><FONT face="Comic Sans MS" =
color=#000080
size=3><SPAN class=343060314-23062005></SPAN></FONT> </DIV>
<DIV dir=ltr align=left><FONT face="Comic Sans MS" =
color=#000080
size=3><SPAN =
class=343060314-23062005>Del</SPAN></FONT></DIV><FONT
face="Comic Sans MS" color=#000080 size=3></FONT><FONT =
face="Comic Sans MS"
color=#000080 size=3></FONT><BR>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000080 =
2px solid; MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader lang=en-us dir=ltr =
align=left><FONT
face=Tahoma></FONT><FONT face=Tahoma></FONT><FONT
face=Tahoma></FONT><BR> </DIV>
<DIV></DIV><FONT face=Arial color=#000000 size=2>
<DIV>
<DIV> Ron</DIV>
<DIV> 8 mm /.320ish is on the thin side for a =
9ft
grand of any make . A board this thin doesn't really need =
much
thinning. In fact it's probably not thick enough in the =
treble. I'm
unaware of the German factory's rhetoric on panel thinning. I'm =
guessing
it sounded a bit thin? grin</DIV>
<DIV> Regards</DIV>
<DIV> Dale</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue =
2px solid"><FONT
style="BACKGROUND-COLOR: transparent" face=Arial =
color=#000000
size=2>Very often the factory line doesn't match the actual =
product. How
<BR>often have we heard about the tapering of sound board panels =
from
<BR>S&S. They may have done it at some time but . . . The =
original
board <BR>which I pulled from a 1962 Hamburg D last year had a 8 =
mm
thick panel <BR>everywhere. I still have the original panel at =
the
workshop.<BR><BR>Ron
O.</FONT></BLOCKQUOTE></DIV></FONT></BLOCKQUOTE></FONT></BLOCKQUOTE>
<DIV></DIV>
<DIV><FONT face="Comic Sans MS" color=#000080
size=3></FONT> </DIV></BLOCKQUOTE></FONT></BODY></HTML>