---------------------- multipart/alternative attachment On Jan 11, 2006, at 12:38 PM, Ric Brekne wrote: > ... > Its really goes a bit deeper then what Bob pointed out if you stop =20 > and think about it. As Ed hinted at, there is something amiss with =20= > the whole <<second partial>> of the tuning fork to begin with. A =20 > few people threw out a couple statements.. one even declared that =20 > tuning fork manufacturers dont spend any time tuning this frequency =20= > around 880Hz. The truth of the matter is that it simply doesnt exist. This is incorrect, in practice. Attached here is a spectrum analysis =20 of the same John Walker fork that I measured earlier with RCT =20 Pianalyzer. The 2nd partial may have vanishingly low amplitude, but =20 it is there. It exists. =EF=BF=BC > A bit of time looking at the physics of tuning forks reveals that =20 > they function more or less like clamped bars, and that the first =20 > overtone is found somewhere between 1/5 and 1/6 the length of the =20 > tines. The relevant frequency is wayyyy up there. In short... the =20= > tuning fork has no frequency around twice the fundamental. It aint =20 > there period. At least one post more or less pointed that out, and =20 > Ed was on this tact as well I think. > > But to the point. The fact is that when playing F3 and sounding =20 > the Tuning fork at the same time... a definite and unmistakable =20 > beat circa at 880 Hz is heard. Less obvious is a much slower beat =20 > at 440... difficult to discern but there. Now since the fork does =20 > not sound at 880, and F3 does not have a frequency at 440... =20 > neither of these beats can be explained in terms of coincident =20 > partials. Period. This is not as not as clear cut as your "period" suggests. 8^) > All argumentation using coincident for or against using F3 are =20 > then simply invalid ! No, a weak 2nd partial is not the same thing as no 2nd partial. > We have to first explain where the unmistakable beating comes from. As noted by at least one, this beating can be weak, consistent with =20 the fifth partial of the piano's F3 beating against the weak 2nd =20 partial of the A fork. > Now I cant do that.. beyond a bit of honest speculation. What I =20 > think is happening is that we are hearing the forks 440 Hz being =20 > interfered with by F3's 5th partial at around 880 Hz. Whether its =20 > something akin to a difference tone or some similar phenomena I =20 > cant say. But it seems clear that the reference frequency must be =20 > the forks 440Hz. THAT is what F3 is beating against one way or the =20 > other ! Doubtable. > As such, the control intervals relative beat rate to this is of no =20 > consequence whatsoever. What is of consequence is the partial of =20 > the note being tuned then. If its A4 then we are dealing with its =20 > second partial which ends up at exactly twice 440Hz. The resulting =20 > A3(2) will be flat after the transfer. If however A3 is tuned =20 > directly from the fork and F3 then its second partial will be at =20 > 440. This explains why Susan and others get so close every time, =20 > and why David Renaud's experiment resulted in A3 being flat by the =20 > exact degree of inharmonicity A4's 2nd partial This is a bit mixed up. If you tune a piano's A4 to zero beat with an =20= A440 fork, you don't necessarily need any check at all if you are =20 very skilled. The same would be true of the piano's A3; if you tune =20 it to zero beat with an A4 fork, you may not need a check note at =20 all, which is a good thing since the coincident partial between the =20 piano's F3 and A3 are at F5, the 4th partial of A3 and the (weak) 2nd =20= partial of the A4 fork. In other words, if you are skilled at zero =20 beating a fork with an piano's A3 or A4, you may tune an accurate A =20 in spite of using an inappropriate check note. 8^) I suggest that =20= this is a reasonable explanation of Susan's success. > Listen to the following wave file which is comprised of 2 sine =20 > waves of equal strength. Frequencies of 873 and 440 Hz. > > http://www.pianostemmer.no/music/FTHREE.wav > > Now these are sine waves with no overtones per se... yet there are =20= > at least 2 easily discernible beat rates. This should be proof =20 > enough that beat relevant beat rates can occur in the absence of =20 > coincident partials. No, Ric. Sine waves, at least the way I was taught 30 years ago are =20 more imaginary ideals than they are real, kind of like equal =20 temperament. LOL It is extremely likely that the waves in your example actually have =20 partials. The most likely explanation of the beats then is simply the =20= 2nd partial of the 440 tone at 880 beating 7 bps against the 873 =20 tone. That's the way I hear it, anyway. > For what its worth.. here is a screen shot showing the combined =20 > wave form of these two frequencies. > http://www.pianostemmer.no/images/FTHREE.jpg > > Second: > "On the other hand, I (sometimes) am happy that people with minds put > together somewhat differently than mine enjoy taking unreasonably =20 > exact > technical devices, and working out _exactly_ where the gnats like =20 > to hang > out. It's nice, on general principles, to know these locations, and =20= > have a > grounding in general gnat-anatomy, though I will always depend on =20 > my ear > instead -- so it ends up as kind of an academic pursuit. Never =20 > mind, we all > have our roles in life ... we all make our various contributions." > > > Thats the intended spirit of this list. Those who succeed in =20 > letting go of accepted so called truths and maintain a questioning =20 > posture even in the face of "accepted fact" are liable in the end =20 > to contribute more to that spirit then otherwise. And this last =20 > discussion is a perfect example of just that. As to whether or not =20= > F3 is usable at all with a tuning fork... one can only say that =20 > arguments citing the lack of coincident partials simply do not bear =20= > on the subject at all, and a clear explaination of what is the =20 > exact source and frequency range of the beats that occur between F3 =20= > a 440Hz tuning fork is needed before one can discount it. You maintain that there is a mystery, but I believe there is no =20 mystery. Sine waves gots partials, and so do forks. 8^) > When all this is shown, and put up against the fact that Susan,,, =20 > like so many many others, is able to achieve a <<beatless>> (for =20 > all audible purposes) rate between A3 and the fork... then it seems =20= > to me that its premature to condemn F3 as unusable with a 440 =20 > fork. We also clearly establish beating phenomena in abscence of =20 > coincident partials here... No such observation is established at all, since there is a clear and =20= simple alternate, and conventional explanation. > This should be of particular interest to adherents of the Virgil =20 > Smith natural beat. Maybe its in this direction we should really =20 > be looking for tuning purposes in the first place... and that =20 > coincidents are at best only a guideline. Sigh. Above you claim as desirable the "letting go of accepted so =20 called truths". In science, they put it differently. While it is =20 certainly desirable to be open to new explanations, it is still =20 essential to maintain skepticism of new theories until they can be =20 shown to provide a better explanation of observed phenomena than the =20 old theories. Ric, you haven't even come up yet with an alternate theory for the =20 source of beats. They come from coincident partials. If you think =20 otherwise then you bear the burden of explaining an alternate source. =20= I say there may be no alternate source. Coincidentally yours, Kent ---------------------- multipart/alternative attachment --Apple-Mail-43--202197987 An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/43/e1/24/a1/attachment.htm --Apple-Mail-43--202197987 A non-text attachment was scrubbed... Name: forkspectrum1.jpg Type: image/jpeg Size: 96579 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/fc/05/ea/ee/forkspectrum1.jpg --Apple-Mail-43--202197987-- ---------------------- multipart/alternative attachment--
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