<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 14 (filtered medium)"><style></style></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1>When I was designing the piano it seemed like a good idea. So my “experiment” involved actually designing and building a piano with the bridge located quite close to the center of the ribs. I was quite pleased with the results. Since I was/am already quite familiar with the results obtained with off-center bridges and here I had the results of one that was nicely centered that—to my ear, at least—performed some better I’m not sure how much more I would learn by taking the strings off one of these pianos and poking around with a tuning fork. <o:p></o:p><o:p> </o:p>Of course the proximity of the bridges relative to the rim (or soundboard liners) makes a difference in how it responds to the vibrating energy of the strings. All other factors being equal the impedance seen by the bridge will be higher the closer it is placed to the rim, but is this what you really want? The closer the bridge is placed toward the rim the more it’s mobility is restricted as is seen at the high treble in hundreds of thousands of pianos of all sizes and at the low bass of small pianos. Is the performance of all those pianos with this design feature all that admirable? Not to my ear, it isn’t. Nor, apparently, is it to many other ears; if it were we wouldn’t see all the discussions about tone problems through the “killer octave” and about struggling to get good performance out of the high treble without lacquering the beejeebers out of the hammers. This is, after all, one of the design features of traditional grand piano design; the bridges are significantly off-center through roughly the upper third of the scale. In my case, by placing the bridge closer to the center of the ribs I was able to avoid these problems and achieve what seemed to me, at least, superior performance. One can, of course, argue that there were/are many other factors at work here and they would be right. Still, after having the experience of building my own piano with this bridge placement were I able to repeat the experience I’d put the bridge right back toward the center of the ribs. Nothing I’ve seen, heard or read has provided anything like a convincing argument to consider doing otherwise. <o:p></o:p><o:p> </o:p>If your only reason for considering off-center placement of the bridges is to control impedances I would suggest that manipulating the cross-section of the ribs would be a better approach. By using whatever combination of width and height you want the soundboard assembly can be made as flexible or as stiff as you want it to be while still keeping the bridge relatively centered and giving it the mobility it needs while still controlling spurious resonances. <o:p></o:p><o:p> </o:p>ddf<o:p></o:p><o:p> </o:p><div>Delwin D Fandrich<o:p></o:p>Piano Design & Fabrication<o:p></o:p>6939 Foothill Court SW, Olympia, Washington 98512 USA<o:p></o:p>Phone  360.515.0119 — Cell  360.388.6525<o:p></o:p><a href="mailto:del@fandrichpiano.com">del@fandrichpiano.com </a>— <a href="mailto:ddfandrich@gmail.com">ddfandrich@gmail.com</a><o:p></o:p></div><o:p> </o:p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'>From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf Of David Love Sent: Thursday, May 24, 2012 7:22 AM To: pianotech@ptg.org Subject: Re: [pianotech] David Love--Centering the bridge--was S&S something er other<o:p></o:p></div></div><o:p> </o:p>First, I do know better than to argue “better or worse” and that’s not where I was headed.  And you may be right about the issue of proximity to the rim versus centerline location.  However, since this question I asked was prompted by a discussion of how to get the high end of the treble bridge more “centered” as if that was desirable, the question is relevant.  Do a simple experiment, take a tuning fork and strike it and place it in the center of a soundboard (unstrung piano will be easier) and time how long until the sound dissipates.  Then do the same thing and place the fork nearer to the rim.  I think you’ll find that it takes longer but do it for yourself.  The impedance characteristics (the rate of energy transfer) is impacted by the location of the energy input with respect to the rim.   Since a centered bridge is as far from the rim as  possible whatever the width of the piano at that section one has to assume that the energy will flow through the system and dissipate more quickly the more centered the bridge is.  With respect to the high treble where sustain is something that is sought after (by some) seeking to center the bridge may not be desirable and may, in fact, be undesirable.  With respect to the lower end of the piano you certainly want it farther away from the rim for reasons mentioned.  For those who have built transition bridges and located those bridges more toward the center of the piano (as in the old three bridge systems), you know that you can encounter impedance problems unless you add support and structure to the transition bridge and even then there can be problems.  So proximity to the rim certainly can make a difference not just in how sections might blend but in the overall quality of the sound as it is impacted by the differences in impedance.  <o:p></o:p><o:p> </o:p>Since the impedance characteristics impact the relationship between the attack and sustain phases, an important consideration in targeting piano tone, I think it’s worth asking whether or not the location of the bridge on a soundboard makes a difference.  I don’t know how to answer it exactly but then if I did I wouldn’t be posing the question.  There are, will be, other differences to be sure.  A wider soundboard will likely have a different rib scale, for example.  A larger area soundboard will also tend to produce a lower frequency when you pound on it.  Does that lower frequency have an impact on the character of the initial percussive attack?  To my ear it seems to but I can’t be sure that’s that actual source of the difference.  <o:p></o:p><o:p> </o:p>A general philosophy of “make no assumptions” has a benefit in that it challenges us to question the way things were done in the past.  But if one is being faithful to that philosophy, it should also bring into question the practices we find ourselves engaging in by virtue of having challenged those old assumptions in the first place.  <o:p></o:p><o:p> </o:p>David Love<o:p></o:p><a href="http://www.davidlovepianos.com">www.davidlovepianos.com</a><o:p></o:p><o:p> </o:p></div></body></html>