Hi Fred, Could you please let us know what notes you chose to measure? I did confirm Coleman's measurement's on one small upright at A5. My methodology was to take ten measurements, toss out the high and low readings and averaget the other 8 readings. I did this at several different partials. It took me over an hour for this one note. I waited at least ten seconds between playing the string so that any lingering vibrations would be dampped out. I have repeated this on other notes without taking nearly as much time did find that sometimes the results would be a sharp unison as well. It appeared to me to be related partly to where the note was in the piano (i.e. A3 would always, for example, be a flat unison, where as F4 would be a "sharp" unison) I would have loved to use a disclavier to excite the string to remove one variable from the experiment. The coupled motion of unisons does fool us so often. I believe the original data suggested that a difference of 1 hertz would "draw" to the same frequency with a three string unison. At 06:24 PM 3/3/2005 -0700, you wrote: > ""<> wrote: > > >>"". >> > > Yes, this is what Virgil says. That a unison goes flat overall when it >is tuned (ie, if one string is tuned “perfectly,” when the >other two are tuned to it, the overall pitch of the unison will be flat of >where the originally tuned string was). And about nine years ago Jim >Coleman confirmed this claim through measurements he made with a new RCT >(RCT had just come out). I questioned Jim when he asserted he had made such >measurements, as I had been unable to measure this phenomenon with my newly >acquired SAT. Jim shared his data (I think this discussion was on >Pianotech), explaining in some detail his methodology. Bottom line: through >careful measurement he had confirmed that a tuned unison was between 0.1 >and 0.2 cents flat of the average pitches of the three individual strings. >In his experiment he had tuned each of the strings to within a measured >tolerance of 0.1 cents of one another. > I more or less accepted that at the time, thinking that RCT was perhaps >more precise than SAT, hence you could read such a small effect using SAT, >but I had to say that a difference of such a small magnitude was not going >to be significant in the actual tuning of a piano. My own take being that >Virgil was using this purported “fact” to justify stretching >octaves. Remember he was asserting at the time (he has since recanted) that >he tuned by listening to the beat between the fundamentals of the two notes >of an octave, and made that utterly beatless. He also said (and wrote) that >this produced pure and beatless triple and quadruple octaves. > Your mentioning this unison/octave “apparent phenomenon” >led me to be curious. Having an RCT of my own now, I decided to try to >duplicate Jim Coleman’s experiment. First step is to tune each string >of a unison within a measured tolerance of 0.1 cents – not a real >easy task. Among other things, it is difficult to get repeated readings for >a single string that are within 0.1 cents of one another. It requires >playing at an utterly consistent level of volume. To have any credibility >at all, one needs to be able to do at least three sample readings of each >string, and have all of them be within 0.1 cents of one another. > But, yes, I was able to do this, and proceeded to read the unison, with >the same care and the same number of samples. And then I went back and >repeated every step (re-measuring each string individually, etc). My >results: I did not confirm Jim’s data. I found what I consider to be >completely random results. Sometimes the three strings played together >would be flat, sometimes sharp, sometimes the same. I am by no means saying >that Jim did anything but a very careful and credible job, as I know him to >be a very careful and utterly honest person. But my results were, shall we >say, varied to such a degree as to lead me to believe that it would need a >great number of repetitions of the experiment to persuade me that there was >any measurable difference between the pitch of three strings sounding >together and the pitches of the individual strings. > I realize that Virgil has taught this in classes, and that he has >demonstrated, and that people have been persuaded by listening to his >demonstrations. I suggest that it is quite possible that, in many >instances, they heard what they thought they did. First, it is next to >impossible to tune a unison within a tolerance of 0.1 cents, and I would >say that it is utterly impossible without the use of a machine. It’s >a problem of resolution – 0.1 cents is at the threshold of where a >pitch produced by a piano string can be measured. They just don’t >produce pitch that clearly defined. Variance in volume, and not that large >a variance, will change pitch more than that. > So my explanation of “how it works” in Virgil’s >demonstrations is that, in fact, the unison tuned is not “absolutely >perfect.” That one of the strings is likely to be, say 0.3 to 0.5 >cents flat of the originally tuned string. And that the aural resolution of >the pitch of three strings of slightly different pitches will be affected >by the factor of phasing (phenomenon where strings will tend to phase with >one another, locking their pitches to one another just like PitchLock >does), so that it is quite possible that the perceived (and measured) pitch >of the entire unison would be lower than the original string, because of >one string having a lower pitch. And the unison might sound very clean. A >unison within a tolerance of 0.5 cents generally sounds >“perfect” to most everybody. But I know most if not all of us >can hear a difference of 0.5 cents in context of octaves, M3s and many >other intervals. > At any rate, I would take Virgil’s assertion with a very large >pinch of salt. Maybe there’s some truth in there somewhere, but it >isn’t what I would give the status of a fact. > Regards, > Fred Sturm > University of New Mexico > PS I would be interested in hearing the results of anyone else who >replicates the described experiment. > > No virus found in this incoming message. Checked by AVG Anti-Virus. >Version: 7.0.300 / Virus Database: 266.5.7 - Release Date: 3/1/2005 Regards, Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T. Non calor sed umor est qui nobis incommodat mailto:pianotuna@yahoo.com http://us.geocities.com/drpt1948/ 3004 Grant Rd. REGINA, SK, S4S 5G7 306-352-3620 or 1-888-29t-uner
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