<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 12 (filtered medium)"><style></style></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1>I’m thinking more about where over a membrane that the energy is input from.  Timpanists or drummers don’t tend to strike their instrument exactly in the middle but more off center.  They do that for tonal reasons.  Center loaded ribs need to be larger to support the same load than non center loaded ribs.  The treble section of the Overs piano doesn’t have the bridge centered in that part of the piano.   Would it sound even better if you could center it?  The impedance characteristics of a diaphragm are different if you strike it dead center than if you strike it off center?  Why would center be better?<o:p></o:p><o:p> </o:p>David Love<o:p></o:p>www.davidlovepianos.com<o:p></o:p><o:p> </o:p><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf Of Dale Erwin Sent: Wednesday, May 23, 2012 6:46 AM To: pianotech@ptg.org Subject: [pianotech] David Love--Centering the bridge--was S&S something er other<o:p></o:p></div><o:p> </o:p>Hi David  Well perhaps there is no for sure answer. How about a thought? Loud speakers are not the same as Soundboard panel shape but they don't build them asymmetrically either. Yet the edges of the paper speaker cones are thinner for more flexible response as should soundboard thickness be as evidenced by the location of rib end cut outs and thinner panel over those cut-outs due to diaphragmatic thinning, which is common.   If it is desirable to have a loud speaker pump energy/sound back and forth when projecting sound, does it make sense that a sound board can do the same more efficiently by having its primary energy distribution point, the bridge, more located in the center of the rib & crown?  I need to use the quality of the sound to answer the question.  I don't always judge sound as better or best but view it like Baskin Robbins Ice cream...37 different flavors , and we all like different ones at different times. Right?.    I am for example blown away by a more symmetrical soundboard shape in Ron Overs piano on the Rachmaninoff album entitled Lilacs. Trebles in a range of timber like I've not hears before. I'll have some more please. &...then there was my experience with my D in Eureka I posted about last weekend. Loved the sound, a different flavor, but a stock shape, basically a tight grain rib crowned Sitka board with white spruce ribbing.  All that to say that... to center or not to center influences the sound and if we like it then whistle a happy tune. Beyond that we simply don't have enough information to predict what one will do over another but there are differences that perhaps can be better quantified by spectrum analysis. Or/and maybe hearing different board shapes in a decent small halls under the fingers of pianists.  Dale<o:p></o:p><div>Dale Erwin... RPT Mason & Hamlin/Steinway/U.S pianos <a href="http://www.Erwinspiano.com">www.Erwinspiano.com</a> 209-577-8397 <tt> </tt> <tt>  </tt><o:p></o:p></div><o:p> </o:p><div>-----Original Message----- From: David Love <<a href="mailto:davidlovepianos@comcast.net">davidlovepianos@comcast.net</a>> To: pianotech <<a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a>> Sent: Mon, May 21, 2012 12:39 pm Subject: Re: [pianotech] S&S K(52) Restoration<o:p></o:p><div id="AOLMsgPart_0_3174ce55-d8f3-4280-9e0d-4e3cd7702518"><pre style='background:white'><tt>There are several claims and apparent assumptions being made about the<o:p></o:p></tt></pre><pre style='background:white'><tt>benefits having the bridge located in the center of the soundboard.  What's<o:p></o:p></tt></pre><pre style='background:white'><tt>that based on?  Why would you necessarily want it centered?  It suppose it<o:p></o:p></tt></pre><pre style='background:white'><tt>sounds logical to have a centered bridge in terms of load bearing--maybe,<o:p></o:p></tt></pre><pre style='background:white'><tt>but what about the acoustical properties and impedance characteristics when<o:p></o:p></tt></pre><pre style='background:white'><tt>the bridge is centered versus when it's not.  I can think of as many<o:p></o:p></tt></pre><pre style='background:white'><tt>arguments for not centering the bridge as I can for centering it.  <o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt>David Love<o:p></o:p></tt></pre><pre style='background:white'><tt><a href="http://www.davidlovepianos.com" target="_blank">www.davidlovepianos.com</a><o:p></o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre><pre style='background:white'><tt><o:p> </o:p></tt></pre></div></div></div></body></html>