[CAUT] Scientific study - Stainless wire (Help!)

[Jurgen Goering]

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.
>
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