Hi, David. David Love wrote: > 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 think that may be another way of describing the same thing? I'm not sure if that isn't > lost in the relatively rapid decay of the treble overall. Pssibly, but that's exactly what we're working on, right? 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. Well, the numbers were just to illustrate, and could never be exact anyway. But, yeah, it's not something you would do all the time for every note, and I doubt one could be very consistent about it. But once you get used to the idea, doing it takes less time than thinking about it. It's easy to try with one string at first, then, once that's working, you'll know which way you moved the first string, so move the second one the same way but less. -Mark > 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 >
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