This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment ----- Original Message -----=20 From: Erwinspiano@aol.com=20 To: pianotech@ptg.org=20 Sent: November 22, 2003 6:50 PM Subject: Chaging upright bridge location & affects Since I need to do extensive repairs anyway I'm considering = building a solid bridge & attaching it to the board where the apron is = currently joined. The current string lengths on note 1 is a very long = 51& 1/2 "& note 28 is 41 & 1/2". If I relocate the bridge It will be = shortening those strings by 2&1/2" on note 1. & 3 & 1/2" on note 28. The = new length will be 49'& 38 & 1/2" respectively. Still long strings. = Because of the half moon shape the longer strings will become even = sorter especially if I use a straight bridge which, would be simpler. = The middle& longer strings would be shorten by as much as 5." I'm looking for feedback from others who have done this or have an = idea about it. A prime consideration for me is, will this improve or = inhibit damping? How will it improve the sound? From what others have = said just attaching it to directly to the board will improve mechanical = efficiency. No argument there, In most uprights the dampers best location would be where the = hammers hit the strings but obviously they can't be there. Also I don't = want to end up with the damper on some nodal point that creates some = harmonic that I can't resolve. In fact perhaps this is why the strings = on most uprights are so long perhaps to mitigate that effect. I don't = know. Will shortening the string push the optimal damping point even = further up the string towards the tuning pins? That to me would be bad. Actually, this is rarely (if ever) a factor effecting the damping = efficiency of vertical pianos. This notion has been repeated so often we = have generally come to believe it even though it has no basis in fact. = It becomes rather like the fundamental political maxim: even the most = blatant lie when repeated often enough will come to be accepted by the = majority as truth. At the risk of sounding like a broken record this subject has also = appeared in one of my Journal articles. Several years back I naively = thought presenting a good working introduction to the basic theoretical = function of the piano damper in a Journal I thought was at least widely = read, if not studied, would do some to dispel this obsolete and = erroneous notion. I was wrong. But to get to the crux of your question: The first issue to consider is = what you are doing to the hammer strike point -- particularly across the = bass/tenor break. Do you have any idea? The second is to consider what = you are doing to the impedance relationship between the bridge and the = soundboard system. How are you planning to alter the design of the rib = structure to accommodate this change? Finally, knowing the speaking = lengths of the first and last notes on the bridge provides us with just = enough information to be dangerous. This information by itself doesn't = tell us anything at all that will help answer your question. How does = this information relate to the overall scale? How will the proposed = changes relate to the overall scale? Are you prepared to knowledgably = make the scaling adjustments needed to blend this new bass scale in with = the rest of the piano? Obviously, I am in favor of modifying existing pianos to improve their = performance. But to achieve good (and predictable) results each change = must be integrated with the overall design of the piano. A lot more = consideration must go into making alterations like this than simply = pondering what might happen to damping efficiency (though evidence = suggests that some manufacturers don't even get this far before making = even more extensive changes). Providing the background to help answer = this question is the whole point behind the all day seminars I give on = the subject. And even with six hours I barely have time to scratch the = surface.=20 Del ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/64/fd/60/0a/attachment.htm ---------------------- multipart/alternative attachment--
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