<!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><FONT id=rol= e_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 mas= s is too much or not enough?   Too much thickness in the treble can giv= e 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 s= ize=3><SPAN class=343060314-23062005>Dale,</SPAN></FONT></DIV> <DIV dir=ltr align=left><FONT face="Comic Sans MS" color=#000080 s= ize=3><SPAN class=343060314-23062005></SPAN></FONT> </DIV> <DIV dir=ltr align=left><FONT face="Comic Sans MS" color=#000080 s= ize=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 suppo= rt 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 y= ou mean thinner, as the compression load a on a thinner board would give up soo= ner. Also most diaphramized bords are 8 mm or less around the perimeter</STRONG></DIV> <DIV align=left></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 s= ize=3><SPAN class=343060314-23062005></SPAN></FONT> </DIV> <DIV dir=ltr align=left><FONT face="Comic Sans MS" color=#000080 s= ize=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 t= he 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> </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> </DIV> <DIV> </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></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 s= ize=3><SPAN class=343060314-23062005></SPAN></FONT> </DIV> <DIV dir=ltr align=left><FONT face="Comic Sans MS" color=#000080 s= ize=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=#0000= 80 size=3></FONT><BR> <BLOCKQUOTE dir=ltr style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000080 2px sol= id; MARGIN-RIGHT: 0px"> <DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left><F= ONT 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 g= rand 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 t= he German factory's rhetoric on panel thinning. I'm guessing it sounded a b= it thin? grin</DIV> <DIV>  Regards</DIV> <DIV>  Dale</DIV> <BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px soli= d"><FONT style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 s= ize=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>wh= ich 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> </DIV></FONT></BODY></HTML>