<html> <body> David Love - Thanks for responding.  I haven't forgotten that you started all this with your Negative Bearing question a few years ago.  Let's see if I can keep this on track long enough for me to understand.  To simplify things a bit, can we agree to acknowledge, then ignore the fact that we cannot determine the original bearing set up from measuring the strung piano? Why does there appear to be this growing consensus that these "after stringing" measurements are deceptive, confusing, and of no value?  Whether or not the board is being compressed  (i.e. stiffened) by one area of the string scale, if I get readings showing zero or negative downbearing in a section of the piano, is it to be dismissed because there is downbearing SOMEWHERE on the board? With regard to transfer of vibrations, can you, David, or anyone else, direct me to recent discussion that supports this view of the irrelevance of downbearing in this process?  (I will scan the past years posts if you cannot.)  If such is, in fact, the case, and if you could create the hypothetical soundboard with sufficient stiffness WITHOUT employing downbearing's compressive function, is there, in your opinion, ANY aspect of the mechanical transfer of energy from string to bridge ( & board) via bridge pin, that would suffer in the absence of such downbearing?   For example, if the string were to traverse the bridge, captured by the pins (horizontally) , but at 1/16th or 1/32' above the bridge surface? And what is the nature of the coupling you speak of? (Bridge translating string impulse)  What is the implication regarding the way the string energy transfers from string to bridge to board?  Did I miss the resolution to that question?  Sorry for all the questions. David Skolnik At 07:25 AM 1/30/2004 -0800, you wrote: <blockquote type=cite class=cite cite>The transfer of vibrations happens due to the coupling of the string to the bridge, not due to any downward pressure of the strings onto the bridge.  That coupling is achieved by the interlocking of the string through the bridge pins .  Whether or not you have downbearing will not influence this coupling.  The downbearing effects the amount of downward pressure on the soundboard.  When the board is compressed it gets stiffer.  The more stiff it is, the greater the impedance (the panel's tendency to resist the transfer of vibrational energy).  The treble end of the board needs to be stiffer than the bass area.  The relative narrowness of the board in the treble region combined with more downbearing at that end produces more stiffness.  The measured bearing can be confusing because you set the bearing with the board only minimally compressed (or not compressed at all depending on your technique).  The amount of measurable beari! ng after the board is strung and loaded will be different than before it is strung.  You can't really tell after the board is strung and loaded what the bearing was at the outset.  The tone of the board will be influenced by the board's response to this downward pressure and whether it achieves through design and execution the proper impedance characteristics throughout the scale.    David Love <a= href="mailto:davidlovepianos@earthlink.net">davidlovepianos@earthlink.net= </a>     <dl> <dd>----- Original Message ----- <dd>From: <a href="mailto:davidskolnik@optonline.net">David Skolnik</a> <dd>To: <a href="mailto:pianotech@ptg.org">Pianotech</a> <dd>Sent: 1/30/2004 3:10:21 AM <dd>Subject: Re: No downbearing ? REVISITED <dd>Almost one month ago, this a question regarding downbearing was raised: <dd>At 04:09 PM 12/31/2003 +0100, Jean-Jacques Granas wrote: <blockquote type=cite class=cite cite> <dd>I have come across a puzzling suggestion a few weeks ago: Namely, that downbearing is not really necessary in order to transfer the vibration of the string to the soundboard panel, the mere "grip" that the string has on the bridge being sufficient to assure this transfer. Would anyone of you with experience in such issues care to comment? </blockquote> <dd>Then, At 10:48 AM 12/31/2003 -0500, John Hartman wrote: <blockquote type=cite class=cite cite> <dd>Yes I believe this is correct. Bearing does not directly influence the transfer of vibrations. What it does is alter the apparent stiffness of the Soundboard and thereby help to control the rate at which the vibrations move from the strings into soundboard. Check the archives for soundbaord impedance.</blockquote> <dd>Then, At 05:25 PM 12/31/2003 +0100, Isaac sur Noos wrote: <blockquote type=cite class=cite cite> <dd>I should say that indeed downbearing is not indispensable, but on most pianos, front bearing particularly produce a more pleasing (fuller) tone. <dd>  <dd>Bearing being not discernable after the strings have been installed, it is often confused with "distance bearing" which indeed is the proof that some pressure exist when it is seen, but on some pianos the soundboard look flat after the strings have been tense (while down bearing exist absorbed by the soundboard) . <dd>  <dd>All depend of the kind o= f ribbing and construction used (flat ribbing vs. crowned ribbing). Most German made pianos are using flat ribs and are very sensitive to humidity changes when the soundboard is in good condition, so the go out of tune easily in that case. these instruments need less down bearing than the ones which are u! sing crowned ribbing (Bösendorfer for instance). <dd>The flat ribbing method "is said" to produce stiffer soundboard assembly, while curved ribs need to be pressured more to obtain the necessary stiffness. That is what I have understood, very crudely  I confess, from the different conversations on those matters.</blockquote> <dd>By the second (Isaac sur Noos's) response, what was a potentially illuminating or controversial discussion, was re-routed to yet another review of crown and the crowning process.  None of the subsequent contributions sought to address the original question (in fact or in spirit), or to clarify John's response.  Here is some of what I felt was missing: <dd>Jean-Jacques, what was the original source of your 'puzzling suggestion'?  (previous posting?)  The mere "grip" , as you described would, presumably, refer to the side bearing of t! he bridge pins.  This would seem to promote  the theoretical conclusion that the energy is channeled from string to bridge exclusively by the bridge pins; that the function of the front  edge of the bridge top may simply be to limit the downward excursion of the string.  Does it have any role in creating a reflective terminus of the string? And if so, how much force is required to prevent  (or control?) energy leakage to rear string segment?  Is it presumed that  the transfer of energy would be unaffected by the presence of either positive bearing, no bearing, or, for that matter,  negative bearing, as long as the bridge pins held onto that string,? <dd>John's response is, I think, unintentionally misleading. He first suggests that Jean-Jacques's  statement is correct, but then immediately attributes to downbearing the [important?]ability of controlling "the rate at which the vibrations move from the strings into s! oundboard". If there is a point of differentiation to be made here, it seems inordinately subtle, compared to the resulting impression conveyed that downbearing is not an essential component in piano design and engineering. Unless that is the meaning that is intended!? <dd>Finally, before Isaac Sur Noos directed the discussion towards crown, he made some comments which, if I understand them correctly, are additionally confused: <blockquote type=cite class=cite cite> <dd>I should say that indeed downbearing is not indispensable  but on most pianos, front bearing particularly produce a more pleasing (fuller) tone.</blockquote> <dd>To summarize then, downbearing isn't essential, unless you want the piano to sound good.?? <dd>With regard to downbearing being discernable, or measurable  (see quote above)... what IS measurable is, as he puts it, distance, or string deflection,  I may not be able to tell how much the board has flattened in response to X amount of original downbearing, but if there is no measurable deflection, there is no downbearing.  Is this not true? <dd>Thoughts? <dd>David Skolnik </dl></blockquote></body> </html>