<!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 6.00.2800.1226" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003>Terry Farrell said:</SPAN></FONT></DIV> <BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid"> <DIV><FONT face=Arial></FONT> </DIV> <DIV><FONT face=Arial><SPAN class=171174021-05102003><FONT color=#0000ff size=2> " </FONT></SPAN>When flat ribs are glued to a very dry flat panel, no force vectors exist in the system. As the panel takes on moisture and the ribs bend, the ribs will <EM>always</EM> be trying to pull the panel flat. Period. If that assembly has crown, the ribs will <EM>always</EM> try to go straight by pulling down on the panel. The compression forces in the panel are the only thing that has provided the force necessary to bend the rib into a crown. Whether or not you ever load that soundboard on top, the ribs will always be fighting the panel compression to go flat. When you do apply a load to the top of the soundboard, the compression on the panel will increase, but the ribs will do nothing other than still try to go flat. As the crown lessens under increasing load, the ribs will pull downward a bit less, but only because they are being bent upwards less by the panel.<SPAN class=171174021-05102003><FONT color=#0000ff size=2> " </FONT></SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003>The way I see it, the reason why we have the killer octave problem with mostly CC boards, is that the crown produced with the panel's growth will be kind of proportional to the lenght of the ribs. So, with this method the treble that always have shorter ribs than the tenor will have less crown in the beginning. Since compression will affect the board's with aging, we end up with a dead killer octave and a no crown zone exactly where the ribs get shorter...in the killer octave.</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003>So I guess there is no way to have a decent board assembly that will have a predictable lifespan with the Compression Crowned method. It's physics.</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003>Again, I might be wrong, but I think I've seen the light.</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003>Marcel Carey, RPT</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003>Sherbrooke, QC</SPAN></FONT></DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003></SPAN></FONT> </DIV> <DIV><FONT face=Arial color=#0000ff size=2><SPAN class=171174021-05102003></SPAN></FONT> </DIV></BLOCKQUOTE></BODY></HTML>