Richard Moody asks: >...how accurate are ETDs when measuring partials? Richard, there is no intrinsic difference in accuracy when measuring partials versus measuring the fundamental. Sometimes the partial has more falseness than the fundamental and that makes it harder to measure, but the same thing might happen with the fundamental. You seem to be assuming that ETDs measure partials in a different way than they measure the fundamental. They don't. They just pick a different frequency. Now granted that the target frequency calculations in the ETD may involve inharmonicity, and to the extent that the inharmonicity model is "inaccurate" for the string being measured, the ETD may be setting goals that are "inaccurate". But this has nothing to do with measurement accuracy. The real question was about partials changing on the same instrument. You go on to state: >But before all this speculation I would like to see it >demonstrated that 2 different machines show the same variance >a first machine shows. With the wide spread availability of >ETD's this should be easy to accomplish. If you are looking for a way to disprove that certain things affect inharmonicity, this is not the way to do it. Using several different ETDs would just add more variables to the experiment and further complicate the results. It is very easy to make this determination using just one ETD. If the ETD itself or the way it is used is causing the apparent variations, then those variations will not be correlated with the factor under investigation (such as hammer blow). If statistics bear out the correlation, then it is not hard to imagine mechanisms that explain the effect. My personal opinion is that if these inharmonicity effects exist (from hammer blow and voicing), they are not large enough to be of any consequence to everyday piano tuning. -Robert Scott Detroit-Windsor Chapter, PTG
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