<html> <body> Ric - This was one (just one) of the reasons I was so sad at not being able to be in Rochester. I hope Steve Birkett does make the DVD available. You said a few things: <blockquote type=cite class=cite cite="">the initial pulse and reflections look a bit more like a Gausian [sic] wave then a straight traveling wave</blockquote> First, just for those who may not remember their Gauss: <blockquote type=cite class=cite cite="">A Gaussian function (named after <a href="http://en.wikipedia.org/wiki//wiki/Carl_Friedrich_Gauss">Carl Friedrich Gauss</a>) is a <a href="http://en.wikipedia.org/wiki//wiki/Function_%28mathematics%29"> function</a> of the form: <img src="cid:.0" width=162 height=27 alt="f(x) = a e^{-(x-b)^2/c^2}">   for some <a href="http://en.wikipedia.org/wiki//wiki/Real_number">real</a> constants a > 0, b, and c. Gaussian functions with c2 = 2 are <a href="http://en.wikipedia.org/wiki//wiki/Eigenfunction"> eigenfunctions</a> of the <a href="http://en.wikipedia.org/wiki//wiki/Fourier_transform">Fourier transform</a>. This means that the Fourier transform of a Gaussian function is not only another Gaussian function but a <a href="http://en.wikipedia.org/wiki//wiki/Scalar_%28mathematics%29"> scalar</a> multiple of the function whose Fourier transform was taken. Gaussian functions are among those functions that are <a href="http://en.wikipedia.org/wiki//wiki/Elementary_function_%28differential_algebra%29"> elementary</a> but lack elementary antiderivatives.</blockquote>(quoted from Wikipedia) Oh, that's right.  Now I remember.  Okay then, well, if it's Gauss we're talking about, then, to quote Samuel Jackson in Pulp Fiction, "Please, allow me to retort".  What?? or, to paraphrase another quote from the same source; "What does a Gaussian wave look like?" Anybody starts throwing Gauss around on this list better be willing to simplify it for us morons, even if that's only a couple. (Smiley faces not operational) Honestly though, it may have to wait until Birkett or someone else writes "Elementary Gauss for Piano Technicians", but until then,   maybe you could elaborate and simplify, all at once. You also paraphrased Birkett along the lines of  "namely that if you can't measure it or photograph it...".  Well, I've been wondering about something for quite some time, but haven't known exactly how to pursue it, though the information is probably right under my nose, (as in previously discussed on this list).  How does wire look (and act), molecularly, at rest, and how does that molecular structure and behavior change as tension is applied, and as it approaches and attains breaking point?  On what level does the behavior of the wire change as a response to material imperfections (in fact, how uniform is the molecular structure of piano wire?brand to brand?) or to physical distortions (bend / crimp) or to the physical process of termination?  Did Birkett speak of making any observations along these lines? Lastly, I'm not sure what you mean by: <blockquote type=cite class=cite cite=""> I am wondering at this point whether or not the <<definition>> or focus of the termination at the bridge is what is at work here.</blockquote> Sorry to have missed you on your trip to the states, and I hope the cinematic references were not too obscure (or too obvious) for you.  Any of you. David Skolnik At 05:30 AM 8/13/2006, you wrote: <blockquote type=cite class=cite cite="">Hi Tim, Cy and John. Interesting we have already what looks to be 3 different interpretations of what is happening to the pulse.  Seems clear to me that the reflection would be influenced by the whatever angles are involved in the clamp. I did a kind of macro experiment a while back with a rope terminated different ways and the effect was pretty clear.  A slanted pin caused the pulse to be deflected differently then either a purely horizontal or vertical. You could see an initial sideways jerk as the pulse repelled from the slanted pin.  Perhaps this causes some degree of loss ? The high speed photography that Dr. Birkett took was quite revealing indeed. I only got to look at a couple things he did the first two nites of the convention. One seires done with Tim, and another single experiement I helped with on a standard configured piano.  Some of the thoughts I've been having about what happens to the initial pulse in general seemed supported.  For one thing the initial pulse and reflections look a bit more like a Gausian wave then a straight traveling wave. I didnt get to see a side by side comparison of a wapin vs a standard bridge pin... and no doubt one would have to study closely for some time to start drawing any conclusions... but Birketts take on these kinds of discussions is something I like immensely... namely that if you cant measure it or photograph it... then there isnt a lot of reason to start making sweeping declarations about how a thing functions. Anyways.. back to wapin ...  I am wondering at this point whether or not the <<definition>> or focus of the termination at the bridge is what is at work here. A clearer focused pulse reflection could result in less loss and more returned energy for the string... ? It was an interesting afternoon and evening I spent with Tim and Dr. Birkett in Rochester thats for sure.  Thanks to the both of them for allowing me some hands on time in a bit of what both do. Cheers RicB</blockquote></body> </html>