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If the string terminations on the plate are not optimized for full freedom of the pivot termination principle; yes your strings are more likely to break. If you don't play with a great dynamic range the risk is diminished, but the tone is still of lesser quality.


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I believe Kawai has tested and verified what my specifications and data reveal about V-bar shape. The newest Kawai's I have seen had V-bars shaped to a precise V shape. I don't know if they are doing it on all of their pianos.


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Originally Posted by Jethro
And I think that is one area where a sand casted plate may have an advantage over the V-pro acoustically speaking. A good plate to my understanding is able to take the tons of pressure placed upon it by the string tension and at the same time ideally does not add any unwanted resonances of its own. Though lighter in weight the V-pro is just as strong to take the tons of pressure placed upon it but not hefty enough to eliminate all unwanted resonances. Heavy is good if you to dampen unwanted frequencies. This is my opinion only but there might not be any truth to it so I’m wondering if anyone has any thoughts on this.

Makes sense, but you'd first have to know at what weight resonance is an issue. If, for example, there is no discernable difference after a plate surpasses 150 lbs., then having extra weight would not help. Also, is plate resonance necessarily a bad thing? What does it actually do to the sound? How does the resonance interact with the rest of the piano? I think it's tough isolating the tone of a piano to one structural element when the sound is produced by a synergy of the whole. The fact there are pianos with both casting methods that sound excellent should prove that both work.


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Originally Posted by Ed McMorrow, RPT
But the issue of hard castings at the V-bar also makes treble tone more harsh, so even if you don't get your piano tuned like a performance instrument, it affects sound quality.
Lots of things affect sound quality. Listening to the sound made by a piano is the best way to evaluate it.


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I also know how important proper string terminations that maximize the pivot termination are to clear, rich dynamic, sustaining tone because I have solved tonal problems in capo bars by removing the existing strings, reshaping the V-bar to a true V-shape and putting the same strings back in the piano with the end result of buzzing, pinched tone corrected.

That is a form of scientific proof.
It demonstrates that the shape of the v-bar matters. One could even suggest that a harder casting would do a better job of maintaining the shape of the v-bar.

But I have no reason to doubt that there is an optimal shape and hardness for a v-bar.

I also don't doubt that some plates may be designed to be harder. The greater geometric accuracy of vacuum casting may allow thinner plates to be made and these may require a harder material to have the required strength not to bend under string tension. Such a plate may reduce the manufacturing cost and even shipping cost (lighter weight) of a piano. Yamaha and Kawai may even use plates designed that way in some pianos.

But I am skeptical that this is an inherent property of v-cast plates or generalizable to all pianos with v-cast plates. There is too much information available that says otherwise for me to believe that assessment.


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Originally Posted by BDB
I have seen broken strings on a number of different makes of piano. If they are played a lot by pianists who insist on playing loudly (rather than making their audience shut up and listen) and who do not keep their pianos tuned, regulated, and voiced, it happens from metal fatigue. The way the string moves at the capo bar is quite violent, as it whips rapidly from one direction to the other. You can see this if you fasten a slinky at each end and give it a pull and let go. Worn hammers will make that even more violent, since the motion of the string takes on the shape of the hammer, so that if you have a hammer that is squared off from wear, rather than rounded, that whipping is even more extreme. It will also have a harsher sound, which is why as hammers get worn, the piano gets brighter, and simply reshaping the hammers makes a big difference towards restoring the original sound.

This video shows reasonably well how a string moves. Just ignore the commentary and watch the endpoints of the string, and keep in mind that a plucked string is not the same as a string excited by a piano hammer, although it is somewhat similar to a worn hammer with a flat strike point.



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Originally Posted by BDB
I have seen broken strings on a number of different makes of piano. If they are played a lot by pianists who insist on playing loudly (rather than making their audience shut up and listen) and who do not keep their pianos tuned, regulated, and voiced, it happens from metal fatigue. The way the string moves at the capo bar is quite violent, as it whips rapidly from one direction to the other. You can see this if you fasten a slinky at each end and give it a pull and let go. Worn hammers will make that even more violent, since the motion of the string takes on the shape of the hammer, so that if you have a hammer that is squared off from wear, rather than rounded, that whipping is even more extreme. It will also have a harsher sound, which is why as hammers get worn, the piano gets brighter, and simply reshaping the hammers makes a big difference towards restoring the original sound.

This video shows reasonably well how a string moves. Just ignore the commentary and watch the endpoints of the string, and keep in mind that a plucked string is not the same as a string excited by a piano hammer, although it is somewhat similar to a worn hammer with a flat strike point.



A question for Ed. It would be great to have slow motion close up videos of the motion of strings at a V-bar and a U-bar, but would you a go at describing what the dynamics of the "violent" contact between string and metal would be in each case?


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Originally Posted by Withindale
Originally Posted by BDB
I have seen broken strings on a number of different makes of piano. If they are played a lot by pianists who insist on playing loudly (rather than making their audience shut up and listen) and who do not keep their pianos tuned, regulated, and voiced, it happens from metal fatigue. The way the string moves at the capo bar is quite violent, as it whips rapidly from one direction to the other. You can see this if you fasten a slinky at each end and give it a pull and let go. Worn hammers will make that even more violent, since the motion of the string takes on the shape of the hammer, so that if you have a hammer that is squared off from wear, rather than rounded, that whipping is even more extreme. It will also have a harsher sound, which is why as hammers get worn, the piano gets brighter, and simply reshaping the hammers makes a big difference towards restoring the original sound.

This video shows reasonably well how a string moves. Just ignore the commentary and watch the endpoints of the string, and keep in mind that a plucked string is not the same as a string excited by a piano hammer, although it is somewhat similar to a worn hammer with a flat strike point.



A question for Ed. It would be great to have slow motion close up videos of the motion of strings at a V-bar and a U-bar, but would you a go at describing what the dynamics of the "violent" contact between string and metal would be in each case?

I would suggest that the contact on a V bar would only be 'violent' if contact between string an V bar breaks or is made, otherwise the string would be stationary at the contact point (apart from stretching). For contact with the V bar to be lost either the string would need to be lifted off the vbar by the string motion or alternatively the Vbar angle would have to be more shallow than the deflection angle of the string so that contact with the Vbar sides is made. Maybe one or both of those two thing happen but the mechanics of that seem unlikely - I'd love to see a video of the actual motion.

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Re. topics like the plate's mass (and v-pro allowing tolerances to by cut), sympathetic vibration, cooling rates, etc, there's actually a lot of interesting stuff already posted in the thread I linked above, and others.

TLDR for those who don't want to search out the threads -- IIRC -- is that all plates are over built to some extent. Hypothetically, if wet sand cast plates are overbuilt by a factor of 3, then v-pro may be overbuilt by a factor of 1 or 2, but overbuilt nonetheless. Also, as noted above, they can be overbuilt to the same extent as a wet sand cast plate anyway, and largely are. Wet sand cast plates should not be assumed to be the "exact" mass necessary to do the job.


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Originally Posted by gwing
I would suggest that the contact on a V bar would only be 'violent' if contact between string an V bar breaks or is made, otherwise the string would be stationary at the contact point (apart from stretching). For contact with the V bar to be lost either the string would need to be lifted off the vbar by the string motion or alternatively the Vbar angle would have to be more shallow than the deflection angle of the string so that contact with the Vbar sides is made. Maybe one or both of those two thing happen but the mechanics of that seem unlikely - I'd love to see a video of the actual motion.

Well, I hope Ed will have something to say about what is going on. Something must be to justify all that filing.

I see an idealised V-bar as a point contact. Your description certainly conforms with that.

A U-bar will have an arc of contact with the string, and the length of the arc will vary with the vibration of the string. If we could see the vibrations at the bar, we might be surprised at how complex they are.


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Originally Posted by Withindale
A U-bar will have an arc of contact with the string, and the length of the arc will vary with the vibration of the string. If we could see the vibrations at the bar, we might be surprised at how complex they are.

I've wondered about this same thing (tiny changes in string length, and how perceptible they are). I recall the same thought in an old thread about bridge pin diameter. The larger the diameter or wider the curve, the more the impact I would assume. Although I wonder if broader contact and less "angular" points of contact might offer other benefits, like tension crossing more easily (for tuning and stability). But I'm only theorizing.


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If my memory is accurate, the straight strung Chickering 33B I owned 35 years ago used agraffes for all strings.


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In high speed video of struck piano strings the amplitude very near the terminations is nearly zero to the eye. Nothing "wild" to see there, after all piano wire is very stiff.

My proof for V-bar shape is from taking a piano that had string buzz issues at the V-bar. Carefully removing the strings. Reshaping the U-bar to a V-shape with a 1mm string contact point. Installing the original strings back, and tuning and spacing everything back up.

Buzzes were gone.

Also seeing some old Steinway's and M&H pianos with a true V-shaped V-bar and no string buzzes or breakage in spite of practice room use.

Same issue with agraffes except the work of removing the existing strings, shaping string holes and reinstalling the same strings is too high and risky. In those case replacing the string must be done at the same time for serviceability guarantee.


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Originally Posted by Ed McMorrow, RPT
Buzzes were gone

What more to say? It works.

I suppose physicists might look at wave reflection. They might say a true V-shape approximates to a single point of reflection as opposed to many where the string is in contact with the U-bar. Multiple reflections that interfere with each producing buzzes.

As a schoolboy I went to hear Sir Laurence Bragg give a Christmas lecture at the Royal Institution on dislocations in metals (where lines of atoms break). As these were not easy to see he devised a bubble raft as a model. All the bubbles were the same size and floated in neat rows covering the surface of the liquid. There were a few dislocations and these would move from one row to the next.



As you can see theses dislocations move around like tadpoles. Once they congregate in a metal it can deform and break. One can imagine that happening over time in strings at U-bars - to many tadpoles swimming in all directions!


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