[pianotech] Some Observations & Questions Regarding Partials & Inharmonicity

Tyler Ferrari tylerferrari at hotmail.com
Tue Mar 17 00:24:03 PDT 2009






I have a few questions and observations I wanted to post,
and hope to hear some replies.



If a string is said to have a lot of inharmonicity, does that mean that all of
its partials are always sharp? As the partial being listened to moves further
away from the fundamental, does it get progressively and proportionately
sharper (as if it were based on a simple multiplication of constant), or does
it get 'exponentially' sharper depending on how much inharmonicity the string
has? I'm finding when listening to certain strings that certain partials are
sharper than others (in a single string). The octave partial in a single string
may be quite close, but the 10ths (or 17ths) (for example) may be quite sharp.
Am I hearing things, or can one partial be quite sharp compared to another?



I don't quite know how to word that question, so if someone thinks they might
have an answer if I can better clarify it, let me know.



Next,



It appears that most notes lower than C4 have partials that are more noticeable
than others, as well as multiple audible partials. How does one choose where to
split the difference, and choose which partial they are going to leave flat, or
sharp? This becomes much more of an art when compared to the simple task of
eliminating beat rates in the fundamental. Obtaining certain beat rates when
listening to the fundamentals appears to be child's play compared to the task
of choosing which partial to use as the reference for the quality of the
unison, as well as the quality of an interval being played. Listening to the
beat rate between fundamentals when playing an interval (at least in my case)
does not provide me with the best sound. I usually need to add a slight beat to
the interval to remove the issues with the partials that appear to be beating a
rate much greater than the fundamental.



It appears that at the cost of introducing a small beat rate into the
fundamental, I can reduce the beat rate of the partials by a much larger
amount. That seems like an advantageous trade-off. I don't believe that it is a
proportional reduction. If I introduce (for example) .5 BPS into an octave, I
may in fact reduce a particular partial's beat rate by 3-5 BPS. I'm certain
that I'm hearing this, and it really makes a world of a difference when trying
to objectively view the 'quality' of an interval.



I've been reading the discussions and information that people have been posting
regarding 'whole note' or 'whole tone' listening, or tuning. There's a lot of
information and reference to information that I don't understand, but here is
what I have to say about that.



This may be a bold statement, but this is how it appears to me:



If strings have inharmonicity, they cannot be properly tuned by listening to
beat rates of fundamental tones alone. Maybe I'm totally dropping the ball on
this one, but do some tuners only focus on the fundamental when tuning an
interval or unison? If so, that REALLY does not seem right to me. In my case,
the quality of the note is based on the fundamental beat rate as well as
partial beat rates, and often sacrificing one or the other to obtain the best
possible quality of tone.



Eventually, I will learn the special circumstances with my piano well enough to
be able to know how I want to tune certain unisons and intervals to compensate
for the issues with the partials. That's just practice.



But, I cannot imagine getting the point when I could walk into a customer's
house, hear their piano for the first time and immediately have a good sense of
how I need to tune the piano to best suit its particular situation regarding
partial inharmonicity. A person who is doing that, is someone who I would
consider a master-tuner. Is that the point when you become a Jedi Master Guru
tuner, and you can simply tune a piano by looking at it? haha



Thanks for reading my rant/journal on my findings and observations. I'm still a
newbie, but I think I'm really getting the hang of things. I appreciate the
criticism and support I'll receive from this message.



-Tyler


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