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Why new Instrument sounds better after play??


Mudoe

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"" as to why with a higher neck pitch the player perceives lower tension, whereas lower neck pitch is perceived as higher tension ""

I meant actual open string pitch, as in frequency. By pitch, I did not mean neck angle. The effect of increasing the backward neck angle was only to increase the downbearing force of the bridge.

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jmasters says:

"Nigo said that he noticed something peculiar about a Strad. If he increased the neck angle (increasing the downbearing bridge force) it was necessary to loosen the strings slightly to keep the same pitches of the open strings. I assume he had a method to measure the string tensions. In any case, take that as a given. Also, this situation assumed no change in the string length."

This paragraph leads me to assume that he must have measured the tension in both examples, in order to know about the results producing both more and less tension depending on the neck angle, right?

I'm curious whether you think he actually measured the string tension somehow (as opposed to performing a calculation) and if he actually got a numerical result for each of the two different angular positions of the neck, or would he have measured the tension somehow in one example and gotten a specific (probably non-numerical) result (for example, a specific deflection measurement) and then measured the tension in the other example and gotten a similar comparative result but no specific tension numbers?

Could he possibly have measured how much the string would deflect under tension (tuned up to pitch) using, say, the weight of the violin suspended by one of the strings tightened up to pitch by suspending the violin by any one string at its midpoint and measuring the amount of string deflection ... which wouldn't have given a number, but it would have given a comparative result if he had measured the deflection of the same string at the different neck angle tuned to the same pitch.

Hmmmm, I'm wondering how one could easily measure the tension of a string tuned up to pitch? In this example it wouldn't be necessary to arrive at any specific numbers, it would only be necessary to compare the two examples to see which example actually had the greater tension, right? Or, even just to see if the 'perception' of more or less tension was illusory.

The reason I'm asking is that I'm thinking of following what you guys are talking about with an actual violin, since right off the bat here I'm lost. My thinking and even my experience is that when you raise the neck angle the bridge height increases and the string tension goes up and the violin becomes "tight" playing when tuned up to pitch...

Within a certain "window" increasing the neck angle may increase the volume slightly, but either under or over that "window" very much and any "gains" will be lost.

Or is this not possible to observe without a Strad?

Help me, I'm lost

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Well, the basic rule is that with one string length, and one string, there's one tension to give one note--no other way about it. However, and John will know if I'm using this word right or whether I want another, a violin isn't a perfect structure for that model because there's compliance to deal with as well, because the endpoints of the string aren't actually fixed 100%, expecially at the bridge end. That's where my theory about neck pitch vs perceived stiffnes enters in to it, and probably what also affects Nigo's tuning--high frequency bridge wobble, in short. The more aggressive the neckset, the less stable and self-centering the bridge is. John?

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No, he was not analytical at all. He was an ignorant craftsman. I ask YOU to take the problem and make something of it. I think there is really something there. Maybe it is not profound, but when it is all discussed it will make sense. ("Well, OK" you sound reluctantly hesitant. Perhaps you consider your views beyond this excercise. If so, come out and say it.)

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Yes, I think he likely measured the absolute string tension. He worked with Saconni (who was not an absolute moron). I would say how I would do it. I would have a two-point support for the string and put a known load on it. Then I would measure the deflection with a micrometer and do the trigonometry.

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The point is not that the violin is an imperfect model. it is that the simplistic model if a vibrating string, fixed at both ends, is inadequate to describe the actual situation. (String wiggles bridge) Nothing unstable about this. Nothing pathological. The real situation has to dominate the physics because it is the REAL situation. What happens is just that the second-order correction is not what your first sentence would suggest. Physics is subtle, as I said before.

I still say that the effect is not one of false perception. I am sure I can convince you of this when I give the model I showed Nigo, and if you consider what I just wrote.

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"Well, the basic rule is that with one string length, and one string, there's one tension to give one note--no other way about it. "

The simple vibrating sring as taught in physics 101 makes assumptions. a.) the string has no diameter or stiffness. b.) The string is ridgidly attached at both ends. It is (b.) that is violated by the practical situation of the violin .

also case a.) of course, less important)

One must consider the motion of the bridge...... that means that the actual "node" or stationary point of a vibrating string is behind the bridge. The distance depends on the pitch of course.

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It strains credulity to believe that the compliance of the bridge alters the pitch. It strains it even more to assume that a Strad is significantly different from any other violin in this respect.

The pitch of any given string is, in fact, determined by the string length, tension, and incidentally, vibration amplitude. But you can easily do an experiment. Change the bridge compliance and see what this does to the pitch. Or simply add a big weight to the bridge and see what it does to the pitch. I'm betting nada.

If you do find some effect, the next step is to figure out how this is supposed to improve a Strad. Good luck.

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This should be easy to test. Play the strings and get them precisely in tune by whatever method you feel is good, and then put one of the big heavy practice mutes on the bridge which doesn't touch the string but rather just adds some mass to the bridge. If the violin stays exactly in tune as without the mute then the effect of the bridge movement probably isn't significant as proposed. If the tuning changes at all, then I'd say there's some merit to the idea, and the question because really whether or not there's anything here that can generally improve the sound of violins. I'm guessing probably not, but I can't back that up with anything.

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I'm not quite following your point.

Are you making the statement here that a Strad acts exactly the opposite way from what you would expect in a given circumstance compared to a violin that isn't a Strad?

And that understanding what would cause such a reaction would then enable you to understand the mechanism at work and allow you to probably recreate the results by "whatever" means? If so, it would be a clever way to back engineer the question of what makes a Strad a Strad. Or have I completely wandered off the subject?

Quote:

"One must consider the motion of the bridge...... that means that the actual "node" or stationary point of a vibrating string is behind the bridge. The distance depends on the pitch of course."

Well, common sense thinking would dictate that the main node or nodes of the plucked or bowed string would be at or between the bridge and the nut. Still, since the afterlength must be tuned for proper response, secondary nodes also exist between the bridge and the tailpiece (simultaneously), or else tuning the afterlength would probably have little effect on the bowed string. So, nodes do exist behind the bridge as you say, but also in front of the bridge. The fact is that nodes also exist IN the tailpiece and neck also, and they certainly exist on and throughout both plates. The entire violin vibrates as a "unit". Exactly what are you getting at with that statement?

Have you even made what ever main assertion you are going to make yet? Am I jumping the gun?

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If the bridge is moving, it can't be a node. I'm guessing the node is just a bit behind. Imagine a jumprope with a mark on it two inches from your hand. Your hand is the node; the mark is the bridge--the vibration of the bridge location on the string, transmitted to the top, makes the note happen. But if I'm right about that, then the string would have to be tighter than the actual string length would theoretically define. The flexibility of the bridge at each frequency would dictate how tight the string would need to be for any given note.

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In the several letters that follow, Michael is right. The node is behind the bridge.

Nigo's effect is that the increase of the downbearing force of the bridge decreases the complianceof the bridge/body. The question is "why". Yes, there is a compression of the bridge/body because it is "springy", but this should not make a difference in a first-order linear analysis.

The Nigo effect is caused (as I see it) by this springiness being biased further up the stress-strain curve than a more heavily made violin. That is, where the curve would not be a straight line. (The stress-strain curve is a graph that is initially straight and then starts to bend over.)

For my explanation to Nigo, I drew a string horizontal with the left end (nut) fixed and the other end attached to a mass riding on the famous frictionless rail. Also attached to the mass was a vertical spring. The mass was attached to the middle of the spring. I could pre-stress this string by simply squeazing it. The symmetry left the zero point of the mass unaltered.

I used Michaels picture of the node being behind this rudimentary bridge/body as part of the sketched diagrams. If the spring is linear, the natural vibration frequency of the string-mass-spring assembly will not change even if the spring is compressed.

The fact that Nigo saw his effect showed that the equivalent model now had a stiffer spring. Compressing a linear spring does not make it stiffer. One actually needs a stiffer spring or a "non-linear spring.

That is the same as the violin/bridge structure of his strads being more biased into the non-linear portion of the stress-strain curve. I attributed this to the light construction of the average Strad. That is when Nigo got indignant. But it is the simplest model for the effect. Further complications might illustrate more non-linearities of course. The point is that I am sure he saw something, and I am sure that this model did a good job to explain it.

The reason I thought it might be of interest is because many makers are going back to thinner graduations. The feeling is that most Strads really were light and not later thinned out. Maybe Nigo did not see anything, but if he did, he saw exactly what one would expect him to see.

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For CTviolin ........

I am sure he measured both before and after. He could not calculate it because he did not have the new information; that being the "effect" that he wanted to have explained.

He worked with Saconni and I see no problem with one of them having invented a simple device to load the string and measure the deflection. (It would look something like a Suzuki tuner.)

What you describe in the later paragraphs is actually a rather elegant way to do this with the entire string and not just a portion. The distance to the fingerboard could have been recorded at a given point. He would have needed to account for any weight changes because of neck alterations etc. He would have known to do this.

He would not have needed numbers for the absolute tension, just a comparison of greater or lesser. The more I think about it, the more it seems you may have struck on his actual experimental method.

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This is interesting in that if I interpret it right, I use this concept to set the tension of my bars, and my posts--that is, I fit them as tight as it takes to take out most of the slack, stopping when I notice a marked increase in the resistance of the instrument. Of course, I'm doing this in the opposite direction from what the strings are doing to the top, so perhaps I'm acting against the forces of good. . . though the violins don't sound that way! :-)

I'll have to spend more time thinking about this whole thing. One cause could be that Stradivari's arch design is often very different from his contemporaries in ways I've always regarded as pretty clever.

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To Seth ......... Yes, I think that your idea would find the pitch rise a tiny bit. And it should rise more on a lightly built violin than on a heavy one......... I have never tried this.

This illustrates that the node is behind the bridge by an amount depending on compliance. It does not help explain the Nigo effect, because an "effective length" for a string is meaningful even without a non-linear situation.

But I like your idea. It might prove an effective way to measure compliance...... and that almost has to be a significant thing for tone.

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For Michael

I am sure that there might be many explanations. Especially many interesting conclusions. But I am sure that Nigo saw something. The experience pointed out to me that non-linear effects are likely to be very important. That is not to say that I can point out where and when something significant will turn up. I am just happy that you have seen the gist of the whole story. It could have lots of meaning, or very little. The future may turn things up.

I also think that non-linear effects dominate when one wants to compare a good violin with a great violin. The science types that come up with no results do so because they are all taught with simplified models that elimininate non-linear effects. Non linear problems are now usually solved numerically with computers. In the past, nobody had computers, and things were demonstrated with equations (in 'closed form' as they called it.) You would simplify to the point that you could deal with the equations.

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For Michael....

" a violin isn't a perfect structure for that model because there's compliance to deal with as well, because the endpoints of the string aren't actually fixed 100%, expecially at the bridge end. That's where my theory about neck pitch vs perceived stiffnes enters in to it, and probably what also affects Nigo's tuning--high frequency bridge wobble, in short. The more aggressive the neckset, the less stable and self-centering the bridge is. "

Actually, I don't think stability is an issue. Your first mention about compliance is the heart of the matter. The point is that I think that Nigo saw the compliance decrease when he increased the downbearing force. (or as I like to say, the input impedance increased.)

This shortened the effect length of the string. You must be acquainted with effective string lengths through the practice of slanting the fret on a guitar bridge. (Of course I know you are acquainted with it because you gave a good description in one posting.) Showing a bridge like that to someone would be a good example that the there is an effective string length that varies with each string.

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As to fitting bars and posts, a non-linearity might be important but not to the extent that the spring balances downbearing force....... (this can be explained by a simple spring in the bar and post/back) but the tone might be affected through a change in the compliance of these things through pre-stressing.

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And to all......

I apologize for giving short shrift to various letters. Also, I reread Michaels letters on Vuillaume....... I see that I missed quite a few points here and in all the other letters. It was quite late, I was tired and irritated.

But I hope that this compliance thing interests you. The bridge is like a transformer in some respects, and impedance relationships may prove to be quite relevant to good tone. (Well, I am convinced that it is, but I won't push it on anyone.)

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Regarding "loosening up" after not being played. I had a total overhaul on a 40-year old violin done. New bridge, neck reset, saddle lowered, new tailpiece. After I got it back the think would snap crackle and pop during tuning. It was really scary. That went away after about two weeks but it still would go out of tune almost every 10 minutes, very badly. That went away after a couple of months. It took that long to settle down after the work.

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