interesting inharmonicity information

Kent Swafford kswafford@earthlink.net
Mon, 16 Sep 2002 19:27:25 -0500


Irregularity of the lower partials, particularly in the low treble and 
bass is a known phenomenon, and is not limited to verticals. I suspect 
that it would be fair to say that all pianos exhibit this irregularity, 
even if the irregularity gets small in finer pianos.

This phenomenon is why there is such an argument between SAT and RCT 
users about using the 3rd or 4th partial to tune in this area. If you 
use the 4th partial, there is less chance of irregularity; but if you 
use the 3rd partial all unexpected levels of inharmonicity are 
automatically compromised between the 4:2 and 2:1 relationships when 
tuning the octave. (Of course, the Verituner contributes its own unique 
method for tuning the tenor.)

Kent Swafford

On Monday, September 16, 2002, at 09:50 AM, Ron Koval wrote:

> But, when I tested an upright, things started to get interesting.  
> From about C4 and up, I still found an nice predictable pattern to the 
> Ih data.  Going down into the wound strings, it was if some drunken, 
> inked spiders had stumbled across my page!  The single partial that 
> the piano had been tuned to was fairly linear, but the other partials 
> (this is the important part)ESPECIALLY the lower partials were all 
> over the map.
>
> What this means, is that anyone hoping to gather information about an 
> aurally constructed alternate temperament would get the best results 
> doing their measuring above C4.  Also comparing only the lower partial 
> pairs from the tenor into the bass may lead to some inconsistancies.
>
> Not all uprights share this tendency, I'm guessing this one is just a 
> nasty example of why some instruments are a little tougher to get a 
> good tuning in place. (subliminal message: try a Verituner)


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