Changing Harmonicity

Richard Brekne Richard.Brekne@grieg.uib.no
Wed, 03 Mar 2004 23:14:24 +0100


Overs Pianos wrote:
>>  > One of those other parameters is Hammer Weight.  It has been 
>> reported to
>> me
>>
>>>  by Vince Mrykalo that increasing the hammer weight reduces 
>>> inharmonicity
>>>  significantly....
>>
>>
>> How?  By diminishing the influence of higher (more inharmonic) partials??
> 
> 
> At 11:59 AM -0500 3/3/04, Sarah Fox wrote:
> 
>>
>> I don't see how the properties of an impulse delivered to a resonant 
>> system
>> can alter the resonant frequencies of that system.
> 
> 
> Neither can I. The four known factors which determine inharmonicity are 
> wire stiffness (including that of the wrap wire in the bass), string 
> tension, the shape of the string termination and the length of free 
> string segment on the other side of the speaking length termination (ie. 
> the duplex or counter-bearing string segment).
> 
> Ron O.

Well... in defence of David... I seem to remember a thread a couple 
years back  that got into how hammer hardness affected inharmonicity as 
measured by RCT.

But even if that is true... I dont see how one can isolate hammer weight 
from factors like density and resiliancy to get at any quantifiable way 
of determining its effect on inharmonicity.

As far as factors that determine inharmonicity are concerned... I also 
seem to remember reading in one of the physics articles I've collected 
these past couple years that pianostring inharnmonicity is can indeed be 
somewhat affected by the condition of the exciting force... something 
about the strength of any given excited partial having some impact on 
the frequencies of others.... I'll have to dig through what I have and 
see if I can find that... but I think the point was that tension, 
length, termination condition, and not speaking segments are static 
values that dont take into consideration the dynamics of an excited 
string, or underwhat conditions it was excited.... I am admitedly a bit 
foggy on this one so I reserve the right to be too far out on a limb on 
this one.. grin..

Cheers
RicB







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