<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> <html> Hi there Tim. Thanks for the reply and the interesting contrast you provide for perspectives on the idea of string coupling. And very refreshing to hear your comments on Bob, Mike, and yourself in relationship to how much science each of us should feel we are capable of invoking in our discussions. My point with bringing up the issue of string to bridge coupling and Wapin was simply to point out that Wapin had brought (successfully me thinks) into question the need for the type of coupling the traditional bridge pin configuration provides. Wapin as I understand it provides significant increase in sustain with some minor loss of what we normaly associate with power. The power if you will is "spread out" or perhaps its better to say that some of it is used to increase the sustain.  This is my understanding of the effect anyways... and it fits well with the two instruments I have heard. What a preconvexed bridge would do would be perhaps another matter entirely. Point being is that the idea that a bridge needs to be slightly angled backwards, and have the strong coupling provided by the traditional  method of installing bridge pins is not neccessarilly the "best" solution after all. It simply provides one kind of sound, and there are perhaps other pleasing sound types available to be explored. Put this into the perspective of the pre-convexed bridge (which perhaps would have the advantage of being better able to resist string indentations over time) one is left with an apparently unexplored possibility that has up to now simply been written off because it has been assumed we need the maximum possible amount of coupling at the notch. Thanks again Tim. I dont feel like I am much of an expert on these things either... but I like to think things through and make sense as best I can out these kinds of things. Cheers ! RicB Tim Coates wrote: <blockquote TYPE=CITE>Richard Brekne wrote: Well, most recently Ron N's reply to a post I wrote just the other day... and it has some merit to be sure. Let me try to explain as best my understanding allows..... Again... the string is not absolutely  terminated to begin with... energy seeps through to the other side of the termination point. And what so ??  Take an extreme example for illustration. What if you had a "bridge pin" 5 mm out from the notch ? Do you think that as much energy would zip down the pin into the bridge compared to if the bridge pin was in the same place as where the string contacts the wood ? What about the energy that goes beyond  the pin here ? Some of that would have to eventually hit the bridge itself and get transferred... and some more would have to go into losses for that short length between. The Convex bridge surface question is really sort of a variation of the same thing. The string on a flat faced bridge is supposed to bend (if you will) over the edge and is trapped there by the bridge pin at the same place...the idea being to provide as total a termination as is possible at that exact point. The termination is a two component thing.. with one component (the bridge pin) at very roughly 90 degrees from the other component (the bridge itself) If you make the bridge convex then you more or less increase the length of the woods component to the termination..... it takes a wider surface on the part of the bridge to terminate the same amount of energy.... with accompanying losses within the string for that little extra wideness.  Now whether this is a bad thing or not is not for me to say... I would point out though that one of Wapins claims is that the flat faced bridge with the angled pinning we most often see yields unnecessarily strong string to bridge coupling, which he sees as a downside relating to sustain. -------------------------------------------------------------------------------------------------------------------------------- It seems to me what is stated here is being applied differently than Wapin  Co., LLP website states: "The Wapin Technology, U.S. Patent  #6,100,457, is a new way to attach a string to a bridge on a piano.  For centuries piano makers as well piano manufacturers have understood the need to provide a secure coupling for the string as it passes over the bridge. Wapin has this same coupling but due to the unique bridge configuration, more energy is reflected back to the string creating less of a dampening effect than the traditional arrangement." The Wapin Bridge idea is not that more INITIAL energy gets past the bridge pin and into the bridge.  The idea is that more INITIAL energy is reflected back onto the string.  The string vibrates with more intensity.  The bridge receives an increase of energy as the strings have increased energy.  It is as if a car is powered by the engine exhaust rather than the engine.  Perhaps I'm not using all the correct terminology, but with classes I teach I have to speak in a language most can understand. The clarification I'm trying to make is the Wapin Bridge is relying on the string itself to increase the sustain.  The bridge is a secondary part of this.  I don't pretend to be a scientist.  But this is how it has been explained to me by people I highly respect. Michael Wathen doesn't pretend to be a scientist.  We have relied on true scientists to start figuring this out.  Yesterday I spent an hour and half talking with Michael about Bob Coleman's work on Wapin.  Michael is a piano technician and has a Masters degree in mathematics.  He doesn't understand half of what Bob Coleman is studying.  I don't pretend to understand the math behind this stuff.  I can believe Bob Coleman knows what he is talking about.  Have any of us designed and implemented the audio programs he did for NASA?  How many of us were doing piano research 40 years ago with electronic equipment from NASA and the leading piano acoustical researchers of that era?  I think he has game when it comes to studying the piano. Richard,  I really like reading your posts.  Don't get me wrong.  And please don't think I'm some expert.  I have been around Wapin for 5 years and have learned a few things from others. Tim Coates Wapin Co., LLP  </blockquote>     -- Richard Brekne RPT, N.P.T.F. Bergen, Norway <A HREF="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> <A HREF="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broadpark.no/~rbrekne/ricmain.html</A>  </html>