<HTML>In a message dated 12/30/2001 7:34:18 PM Pacific Standard Time, Erwinspiano writes: <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Subj:Re: Piano Rims ./soundboard stiffness Date:12/30/2001 7:34:18 PM Pacific Standard Time From:<A HREF="mailto:Erwinspiano">Erwinspiano</A> To:<A HREF="mailto:pianotech@ptg.org">pianotech@ptg.org</A> . <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px"> Del writes > > >Typically the loss of sustain time due to a low-mass, > >low-stiffness rim is countered by making the soundboard thicker and the ribs > >a bit stiffer. (Though ribs don't really have much effect on tone > >performance through the last couple of octaves in the treble.) </BLOCKQUOTE> Phil Ford <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">> Why do you say that?  Should the ribs be removed in > this area?  What then?  Make the board a little > thicker? 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.      Del        Hi   Del 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.</BLOCKQUOTE>    It's clear from the diagram you posted that in radial version boards the soundboard grain and ribs don't <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">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</BLOCKQUOTE>  If the ribs have little to do with stiffness/impedance and tone production up high it would <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">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?</BLOCKQUOTE>        My experience is that too much stiffness can make the board a little stingy in the trebles including the killer region.  <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">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  The on going question is how stiff is stiff enough?  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.         I love this stuff.  Best--------------------------------  Dale Erwin</BLOCKQUOTE> </BLOCKQUOTE> </HTML>