---------------------- multipart/alternative attachment 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 bearing 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 davidlovepianos@earthlink.net ----- Original Message ----- From: David Skolnik To: Pianotech Sent: 1/30/2004 3:10:21 AM Subject: Re: No downbearing ? REVISITED Almost one month ago, this a question regarding downbearing was raised: At 04:09 PM 12/31/2003 +0100, Jean-Jacques Granas wrote: 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? Then, At 10:48 AM 12/31/2003 -0500, John Hartman wrote: 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. Then, At 05:25 PM 12/31/2003 +0100, Isaac sur Noos wrote: I should say that indeed downbearing is not indispensable, but on most pianos, front bearing particularly produce a more pleasing (fuller) tone. 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) . All depend of the kind of 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 using crowned ribbing (Bösendorfer for instance). 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. 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: 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 the 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,? 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 soundboard". 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!? Finally, before Isaac Sur Noos directed the discussion towards crown, he made some comments which, if I understand them correctly, are additionally confused: I should say that indeed downbearing is not indispensable but on most pianos, front bearing particularly produce a more pleasing (fuller) tone. To summarize then, downbearing isn't essential, unless you want the piano to sound good.?? 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? Thoughts? David Skolnik ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/6a/47/8a/3c/attachment.htm ---------------------- multipart/alternative attachment--
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