<html> <body> Ron, Phil, Ric, others - At 09:05 AM 4/21/2005 -0500, Ron wrote: (David S) <blockquote type=cite class=cite cite=""> <blockquote type=cite class=cite cite="">Phil, are you discounting, or unaware of the Wapin system of bridge pinning?  I know Ron is aware of it, though, given his reaction to my raising it in the context of a previous thread about downbearing, I got the sense that he was not favorably disposed towards it, reasons unknown.  </blockquote>(Ron N) As I've said before, I don't see a need for it, nor do I consider a poorly functioning soundboard to be "fixed" by it's application.</blockquote> Why assume the presence of a poorly functioning soundboard?  Or that I or Wapin is proposed as a "fix" for such?  There may very well be no "need" for it.  That doesn't preclude the fact that someone claims to have observed and measured certain phenomena, and created an experiment, albeit in the form of a commercial enterprise, which claims to interact favorably and predictably with said phenomena.  The claims may or may not be accurate, but it seems a bit capricious to dismiss the ideas out of hand, given their applicability to the topic we're discussing. <blockquote type=cite class=cite cite="">(David S) <blockquote type=cite class=cite cite="">As I see it, you need to deci= de, from the beginning, whether your inquiry is directed towards understanding the mechanical processes at work, or the more practical aspect of building something that will continue to function for a reasonable length of time.  For the most part, questions of loosening bridge pins and crushing notches and caps are of the latter direction.  </blockquote>(Ron N) I disagree. I consider these concerns to be inseparable. Trade-offs can't be reasonably assessed without considering function, production cost, and longevity.</blockquote> Maybe I mis-spoke, though our history suggests that my explanation will likely kalso fall short.  I was trying to suggest that it might be instructional to contemplate as clearly as possible the idealized, or theoretical physical mechanisms operating, which could be subsequently compared to the "real-world" issues of materials, unpredictable production, etc. Separate, then synthesize.  In rereading Phil's original post, I realized that I imposed a bit of my own bias in focus of my comments.  Phil actually was contemplating both the practical AND the more theoretical.  <blockquote type=cite class=cite cite="">(David S) <blockquote type=cite class=cite cite="">That an angled bridge pin mig= ht be more prone to causing cap damage than a vertical one is helpful to understanding piano forensics, but it doesn't, by itself, explain the possible differences in acoustic properties of between each.</blockquote>(Ron N) When the acoustic property in question is false beats. I disagree. No other acoustic property has been claimed or discussed.</blockquote> First of all, in the course of most of the recent discussions, I and others have attempted to establish that the classic "false beat" is not the only acoustic phenomena that is observed as a termination anomaly.   However, in the quote above, I was trying to pose the question whether, in purely mechanical / acoustical terms, an angled bridge pin elicits a different response than a straight pin.  Surly there is some merit in asking such a question, especially if the answer turns out to be affirmative.  <blockquote type=cite class=cite cite="">(Ron N) The point is that we can't assume downbearing, so we angle and offset pins to provide a positive termination that's largely independent of bearing. If the above piano had 15°-20° angled front bridge pins in that problem unison, the only tonal problem would have been the generally nasty distortion at higher attack levels in the killer octave that everyone is so used to hearing that they don't even notice, and everyone would have been happy. What I'm interested in is a standard of offset and pin angle that will reliably provide that termination. I'm not particularly interested in establishing minimum tolerances, because I don't wish to build to minimum tolerance, and these tolerances can't be accurately established anyway. There are too many variables.</blockquote> We can't assume downbearing, and we can't assume front bearing, whether caused by wood crushing, poor planing, incorrect setting of bearing, etc.  You say "we angle and offset pins to provide a positive termination that's largely independent of bearing".  What, precisely, IS "positive termination"?  Does it mean that the reflection of waves in all three axis (pl?) occurs at a point which is a singular distance from the opposite string termination? Does it imply a certain ratio of reflected energy to absorbed energy? Does it reference the actual space and surface area that constitutes the termination?  And of course, does it define or quantify the degree of sliding motion of the string along the terminating structure (bridge surface or bridge pin) parallel to the direction of the wave, thus a lateral movement along the bridge edge, or a vertical movement on the pin? Presumably, it implies a reference to all these conditions, and probably more (don't forget longitudinal waves).  Any of these conditions might be less than perfectly fulfilled, possibly with some perceptible or measurable consequence, or possibly not.  For example, how might you imagine the difference in functioning between a string with negative front bearing which is (temporarily or not) held in contact with the edge of the bridge by the slanted pin, and that same string if or when it loses that contact?  Will the vibrating string slide up and down the pin? If it initially did, would it ultimately abrade a groove or otherwise create a surface which precluded any movement, thus effecting a terminating point for both horizontal and vertical waves?  As an attempt to understand the acoustic process more fully, I see no fault in considering such models of inquiry, even if you choose to build your product with multiple layers of insurance. David Skolnik </body> </html>