<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=iso-8859-1"> <META content="MSHTML 5.50.4134.600" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT color=#000080></FONT> </DIV> <BLOCKQUOTE style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000080 2px solid; MARGIN-RIGHT: 0px"> <DIV style="FONT: 10pt arial">----- Original Message ----- </DIV> <DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B> <A title=Erwinspiano@AOL.COM href="mailto:Erwinspiano@AOL.COM">Erwinspiano@AOL.COM</A> </DIV> <DIV style="FONT: 10pt arial"><B>To:</B> <A = title=pianotech@ptg.org href="mailto:pianotech@ptg.org">pianotech@ptg.org</A> </DIV> <DIV style="FONT: 10pt arial"><B>Sent:</B> December 30, 2001 7:34 = PM</DIV> <DIV style="FONT: 10pt arial"><B>Subject:</B> Re: Piano Rims = ./soundboard stiffness</DIV> <DIV><BR></DIV><FONT face=arial,helvetica><FONT size=2>. <BR><BR> <BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px = solid; MARGIN-RIGHT: 0px" TYPE="CITE"> Del writes <BR>> <BR>> >Typically the = loss of sustain time due to a low-mass, <BR>> >low-stiffness rim is = countered by making the soundboard thicker and the <BR>ribs <BR>> >a bit = stiffer. (Though ribs don't really have much effect on tone <BR>> = >performance through the last couple of octaves in the treble.) <BR></BLOCKQUOTE><BR></FONT><FONT lang=0 face=Arial = color=#000000 size=3 FAMILY="SANSSERIF">Phil Ford <BR></FONT><FONT lang=0 face=Arial = color=#000000 size=2 FAMILY="SANSSERIF"> <BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px = solid; MARGIN-RIGHT: 0px" TYPE="CITE">> Why do you say that?  Should the ribs be = removed in <BR>> this area?  What then?  Make the board a little = <BR>> thicker? <BR><BR>With the bridge so close to the belly rail the = stiffness of the soundboard <BR>panel has much more effect on the soundboard = system impedance than do the <BR>ribs. = <BR>      Del <BR>    <BR>     Hi =   Del <BR>That being the case  why is  the more modern/recent = technique of using a spruce rib preferred in the capo treble areas as opposed = to the lighter weight sugar pine version  which was original = equipment?  Also if it is true that the ribs don't effect impedance as = much as the board stiffness does then why so much weakness in the killer regions = or is that the point where the rib stiffness/impedance really comes into = play? My thinking is that right around note c- 6 must be crucial cross over point.</FONT><FONT lang=0 face=Arial color=#000000 size=3 FAMILY="SANSSERIF"><BR></FONT><FONT lang=0 face=Arial = color=#000000 size=2 FAMILY="SANSSERIF">    It's clear from the = diagram you posted that in radial version boards the soundboard grain and ribs = don't </FONT><FONT lang=0 face=Arial color=#000000 size=2 = FAMILY="SANSSERIF">cross at right angles in the upper trebles creating greater stiffness and = the shorter grain angles in front of the bridge at the belly do as well = (due to the non traditional panel grain orientation off the belly rail ). I = think I'm starting to get it </FONT><FONT lang=0 face=Arial = color=#000000 size=3 FAMILY="SANSSERIF"><BR></FONT><FONT lang=0 face=Arial = color=#000000 size=2 FAMILY="SANSSERIF">    If the ribs have = little to do with stiffness/impedance and tone production up high it would = </FONT><FONT lang=0 face=Arial color=#000000 size=2 = FAMILY="SANSSERIF">seem that all this stiffening shouldn't be needed. However the feedback is that the = sustain is so much better in this radial board indicating that a lot of extra = stiffness is needed from the board and the rib to get the improved sustain characteristics. Am I missing something? </FONT><FONT lang=0 = face=Arial color=#000000 size=3 FAMILY="SANSSERIF"><BR></FONT><FONT = lang=0 face=Arial color=#000000 size=2 = FAMILY="SANSSERIF">    My experience is that too much stiffness can make the board a little = stingy in the trebles including the killer region. I find that I personally = like the sound from retaining the sugar pine configuration in the capo areas = but crowning them from roughly a 50 ft radius graduated up to about a 25 = ft. On the last rib. This obviously adds some stiffness the flat ribs = lacked and it seems to have a good tonal balance between attack/power and = sustain/power balance but doesn't make it to tight sounding. I hate subjective = terms <BR>    The on going question is how stiff is stiff = enough? <BR>    My qustions/comments are in relation to = reproducing original designs and not really to redesigns all though I'm sure the = principles are similar and applicable. <BR>     I love this = stuff. <BR>  Best--------------------------------  Dale Erwin</FONT><FONT lang=0 face=Arial color=#000000 size=3 FAMILY="SANSSERIF"></BLOCKQUOTE></BLOCKQUOTE> <DIV><FONT face="Lucida Sans" color=#000080></FONT> </DIV> <DIV><FONT face="Lucida Sans" color=#000080>Personally, I'm not = convinced there is much difference in performance in the top octave or two that can be attributed to the use of spruce ribs vs. sugar pine ribs. I even tried = maple ribs up there once--not much difference I could attribute to those = either. There are so many variables involved in the process and the structure it's = impossible for me to tell what to attribute to what. I've not ever heard of any = controlled tests done to confirm just what changes in performance there might be.</FONT></DIV> <DIV><FONT face="Lucida Sans" color=#000080></FONT> </DIV> <DIV><FONT face="Lucida Sans" color=#000080>The traditional piano = (with its compression-crowned soundboard) depends at least as much on the = internal compression of the wood in the soundboard panel (and the stress = interaction this creates with the ribs) for its overall stiffness than it does on the = ribs per se. With conventional soundboard design the region around C6 is a = particularly difficult area for this.</FONT></DIV> <DIV><FONT face="Lucida Sans" color=#000080></FONT> </DIV> <DIV><FONT color=#000080><FONT face="Lucida Sans">Yes, I think got = it. I should probably have said something like, "<FONT face=Arial>With the bridge = so close to the belly rail the stiffness of the soundboard panel has much more = effect on the soundboard system impedance than do the ribs <EM>in a soundboard = assembly of conventional design</EM>." You might also note in my drawing that the = ribs are a bit closer together than is common.</FONT></FONT></FONT></DIV> <DIV><FONT color=#000080></FONT> </DIV> <DIV><FONT color=#000080>Del</FONT></DIV> <DIV><FONT color=#000080></FONT> </DIV> <DIV><FONT color=#000080><FONT face="Lucida Sans"></FONT><FONT face="Lucida = Sans"></FONT></FONT> </DIV></FONT></FONT></BODY></HTML>