Hi, David. Well, I think the numbers just get in the way. All we're talking about it stopping moving the pitch of the second (or third) string at a frequency that's slightly different from the already-set string. That's not harder than exactly matching pitch, it's just a question of judging when to stop. -Mark Porritt, David wrote: > Not only passing the point of diminishing returns, but even the > theoretical possibility of pulling that off. At C7 a one beat in 5 > seconds (0.2 beats per second) is a change of 0.16-cents. I'm not > embarrassed to admit I can't make a 0.16-cent change in a string at C7. > > dp > > David M. Porritt > dporritt@smu.edu > > -----Original Message----- > From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On > Behalf Of David Love > Sent: Friday, February 03, 2006 8:37 AM > To: 'Pianotech List' > Subject: RE: Bluthner Tuning (long-winded rehash of unison tuning) > > I'm not sure about the illusion of more sustain, but the swelling (if it > can > be controlled) might create a sense that the note actually gets slightly > louder after the attack phase has settled in. I'm not sure if that > isn't > lost in the relatively rapid decay of the treble overall. In terms of > tuning 3 strings slightly off from each other (or even one) there is a > practical element that has to be considered. Trying to hit a target of > 1 > beat in five seconds for the first unison and then splitting the > difference > with the second just seems like you've gone well past the point of > diminishing returns. > > David Love > davidlovepianos@comcast.net > > -----Original Message----- > From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On > Behalf > Of Mark Schecter > Sent: Thursday, February 02, 2006 10:17 PM > To: Pianotech List > Subject: Re: Bluthner Tuning (long-winded rehash of unison tuning) > > Hi Ed. I was thinking about the analogy you used of the swing. It got me > > started thinking about unison tuning, and so I thought I'd throw this > into the mix, for not only you, but anyone else to weigh in on. With all > > due respect, I think the analogy to a swing is not quite perfectly > applicable, and I'd like to explain why, because I think the difference > leads to a different conclusion about the effect of unison detuning. > > (If this post looks too long, just skip to the summary paragraph near > the bottom - sorry!). > > If the swing's period is 5.0 seconds, and you always apply your push .1 > seconds after the swing has changed directions, so that you are adding > force in the same direction the swing is now travelling (this is what I > think you meant), then the period of your push is also 5.0 seconds, not > 5.1 as you suggested. Your push is slightly, but consistently, late, or > out of phase, and therefore is simply adding amplitude, as to a > pendulum. > > If instead you actually did time your pushes to 5.1 seconds, with each > successive cycle you would get .1 seconds further behind the 5.0 second > phase of the swing, until you were actually colliding with the swing > coming at you from the opposite direction. Where at first you had been > adding amplitude, this would gradually change until you were acting > against and cancelling out the opposing force. This is like two clocks > ticking at slightly different rates - they gradually cycle from perfect > synchronization to perfect opposition and back every x units of time. > This of course is the definition of a beat. > > Anyway, I'll get back to the Bluthner, but I need to say more about > unison tuning. I think we can agree that when one string is slightly out > > of tune with another, the rate of the beat that results exactly equals > the difference in their frequencies, and this brings me to my main > point: I have never been able to detect any kind of locking, coupling, > or accomodation of one string to another, and believe me, I've tried, > and I wish I could. (There is, usually, a point at which I give up and > decide the unison is good enough). To me, tuning unisons is like > balancing the edge of one knife blade on the edge of another - there is > no forgiveness, no sweet spot, no "area" of agreement. If the two > strings are even the teensiest bit unequal, a beat arises, if not > audibly in the fundamental, then for starters in the higher partials, > where the difference is multiplied. And here's one point: it is in > manipulating the rise time of this beat that we are able to create the > illusion that the decay time of the note has been increased. > > To be more specific, we could most likely agree that it is only in the > treble, about the highest two or so octaves, that increasing sustain > time is much of an issue, and Bluthner seems to agree because they added > > the aliqout only on the highest 22 notes of their concert grand. (But > never mind Bluthner, this is about all pianos). Lower notes have both > plenty of sustain time, and several or many audible partials, which > leads to another main point: we don't seem to ever talk about detuning > unisons in the middle and lower regions of the keyboard, and I certainly > > don't do it, because the increasing number and audibility of partials > going down the keyboard means that any slight detuning of unisons is > multiplied as we listen and hear higher up the partial ladder. This > creates the motion anybody recognizes as "out of tune" and we therefore > avoid it. So the rest of this focuses on roughly the upper two octaves > only. > > OK. So the treble notes decay more quickly than lower notes, and we > would like to slow that decay, IOW increase the sustain time, and we > think maybe we can trick the piano into doing our bidding by "tweezing" > the unisons. I say that it doesn't work, and that no matter how we tune > or detune unisons, that the best we can do is _create the illusion of > greater sustain_. We can no more make the note last longer than the > input energy through the string-bridge-board-air makes possible, than we > > can make water flow uphill. > > Here's what we _can_ do. Take for example a note whose sustain time is, > let's say, 10 seconds. Tune the first two strings so they sound as one. > Detune the third string, such that the the beat rate is one beat in five > > seconds. So after the note has lingered half its nominal life, the beat > has risen to a peak at a time when, had the three strings been exactly > in tune, the note would have been at a lower amplitude, as it simply > continued to decay toward silence. The "beat rises to a peak" is another > > way of saying "the tone's apparent rate of decay seems to slow for a > while". When compared to a perfect unison, the note seems to sustain > longer - _unless we keep listening_. If we listen for 10 seconds, we > will hear the note seem to sustain better for about 5 seconds, and then > it will drop off _faster_ for the second 5 seconds than it would have in > > a perfect unison, because that's the price we have to pay for the rise > we enjoyed before; the beat is slow, but it goes BOTH ways. The reason > this works to create the illusion of longer sustain is that the music > rarely calls for a high treble note to linger, exposed, for such a long > time, without aid from open strings or other notes being sounded, and > because we have learned not to expect the notes to actually last very > long up there. But it also works only because these higher notes have > few to no audible partials to betray the detuning of the fundamentals, > leaving only the behavior of the fundamental(s) for us to hear. > > How about tuning the three strings to three instead of two different > pitches? This can work if the piano's tone isn't too clear and > transparent to begin with. Tune the first string for the interval, > detune the second string to create the maximum effective rise time > (experiment), then tune the third string between the first two, so that > its rise time with the first string is about half of the second > string's. This spreads the decrease in apparent decay rate over more of > the note's duration, at the cost of clarity in the unison. This effect > is audible, in both a positive and negative sense. You just have to > decide by experimentation whether the benefit is worth the cost. > > So OK, if this works for two or three strings, why does Bluthner bother > to use four? I think it's a carry over from their older, more elaborate > aliquot system with the second bridge for the octave-higher strings, and > > that it gives them a unique feature that appeals to peoples' ideas of > what might make a different/better sound. I can't say, really, but the > way it seems to work best for me is: tune the three main strings to a > perfect unison. (Detuning the three struck strings just creates too much > > vagueness in the tone and I just don't like the sound as well in the > Bluthner, which, with so many open strings, has a _lot_ of > "atmosphere"). Then detune the fourth (aliquot) string just as Ed said. > I'm not convinced, though, that there's any difference between leaving > it sharp or flat, because of everything I said about it just being a > slow beat, but I am going to try to keep an open mind! > > Summary: All I've been trying to say with all of the above is, if you > detune the fourth string so that it creates the illusion of greater > sustain, keep listening as the note decays and you'll hear the rest of > the beat, and subsequent beats, where the price for the effect is paid. > There is no free lunch! > > Sorry this was so long. > > -Mark Schecter > > PS It seems to me that if the frequency of an impelling force is > different from the resonant period of the structure upon which it's > acting, they cannot be in phase at any time _except_ the moment when the > > two peaks coincide; at all other times they are moving in different > directions, i.e. out of phase. Two structures that are in tune can be in > > or out of phase (peaks coinciding or not), but two structures that are > out of tune (of differing frequencies) seem by definition to be out of > phase, unless one is a multiple (harmonic) of the other. Is this not > true? Please explain. Thanks! > > -Mark > > A440A@aol.com wrote: > > >> Greetings, >> I have found that the Bluther's extra string gives me the best > > results > >>when it is tuned just slightly flatter than the unison. I think it is > > because > >>of the phase interaction, operating through the Weinreich-described > > coupling > >>at the bridge, produces more sustain. >> When the frequency of the impelling force (the unison) is lower > > than > the > >>resonant period of the structure upon which it is acting, (the fourth >>string), the two will always be in phase. If the impelling frequency > > is > higher, the > >>two will be out of phase. It is this out of phase arrangement that > > augments > >>sustain. >> Think of pushing a swing; if the swing takes 5 seconds to go > > out > and > >>return, and you give it a push every 5.1 seconds, you will always be > > helping it > >>go away from you. If you push it ever 4.9 seconds, you will be > > resisting > it > >>every cycle. By creating this micro-resistance between the unison and > > the > >>sympathetic fourth string, I believe that it takes longer for the > > unison's > energy > >>to pass through the bridge, thus more sustain. >> If I tune the fourth string higher, the tone seems to be more > > brilliant > >>or louder, but of shorter duration. >>Just a thought, >>Regards, >>Ed Foote >>_______________________________________________ >>Pianotech list info: https://www.moypiano.com/resources/#archives >> > > _______________________________________________ > Pianotech list info: https://www.moypiano.com/resources/#archives > > > _______________________________________________ > Pianotech list info: https://www.moypiano.com/resources/#archives > _______________________________________________ > Pianotech list info: https://www.moypiano.com/resources/#archives >
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