My math is probably wrong on this and I'm sure I will be corrected if that is the case. But as I see it, the difference in string density between Pure Sound and standard wire is less than 0.64% Wouldn't that, according to the McFerrin formula, result in tension that is 0.64% higher? And is less than one percent really enough to make a noticeable jump that much closer to the breaking strength? Help me out on this one... Jurgen Goering Piano Forte Supply (250) 754-2440 info at pianofortesupply.com http://www.pianofortesupply.com On Aug 28, 2007, at 19:30, Richard Brekne wrote: > Hi Jim > > Sorry to be in late on this, and perhaps this has been covered by some > of the others already. But a few points just so. First check out > Juans own website on these questions. He actually has some of the > answers for you already.. at least as far as physical properties are > concerned. Stainless steel wires density is different to standard > steel, which needs to be plugged into any and all formulas dealing > with string characteritics. As an example, McFerrin gives the > following basic formula (in metrics) for Tension (page 26). T = f^2 * > L^2 * d^2 * ((Pi * 7.85 gm)/ 981) The 7.85 is the string density > value for standard piano wire. 981 is the acceleration of a freely > falling body in a vacum... actually 981 centimeters per second per > second. A bit of physics in there... but the point is that the > resulting Tension for standard steel wire all else being equal will be > different then Stainless because the 7.85 is no longer the same value. > For Stainless this value is 7.90 Actually, average density figures > are a bit dodgey in real life... but they serve well as a general > rule. Maclom Rose wire is just under 7.8 I believe just in case that > is of interest. > > So.. basically what this means is that the tension on a Stainless > steel wire for the same frequency, length and diameter as a regular > wire will be higher, and this explains why its breaking tension is > reached quicker. Breaking tension has become understood to be a key > factor in governing piano sound. Too low and the string gets > tubby... rubber bandish perhaps ?.. To high and it gets harsh and > tends to break quickly... :) Inharmonicity can be said to be related > to a strings stiffness... which in turn is among other things governed > by how much tension is on it and the elasticity of the material used. > Juan claimed to me on the phone that inharmonicity of his pure sound > in real life scaling is generally lower if I remember that > conversation right... struck me as a bit odd considering that given > equal frequency, length and diameter a pure sound string would have > higher tension on it.... but then I dont really know how the rest of > it all works in. > -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: text/enriched Size: 2777 bytes Desc: not available Url : https://www.moypiano.com/ptg/caut.php/attachments/20070828/66a638e0/attachment.bin
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