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Anywhere there's stress; possibly not a good idea. For instance I was very struck by a Kinberg (Chicago maker) that had a relatively thick top, except the widest spots on the upper and lower bouts of the top were only around 1.7-1.9mm--but only for about 35mm inwards from the purfling, in vertical crescents, not around the curves towards the Cs or bottom. Thinking about it, I realized that stress-wise, there's probably nothing happening there at all.

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Hi Michael:

I'm trying to think through which areas if left rather thin might be most problem prone on a violin... so far I'm imagining that the section on the top plate, between the bridge and the top block, running about the width of the finger board would be better off if a little more robust?

Best regards,

E

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Aren't most Strad tops thinner than most new instruments? Several of them don't seem to have died over time.

I think wood properties and arching have a great deal to do with what is "too thin", rather than an absolute number.

The big question remains for me: If it stands up at first, and it stands up later, what connection does static loading have for tone?

Nobody seems to be able to say anything about this.

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I'm trying to think through which areas if left rather thin might be most problem prone on a violin... so far I'm imagining that the section on the top plate, between the bridge and the top block, running about the width of the finger board would be better off if a little more robust?

The highly anisotropic properties of spruce will keep stress from spreading out laterally very well... in simple terms, if you draw lines connecting the edges of the endblocks, most of the stress will be there (the eyes of the F-holes also keep the stress centralized). I took a tuned violin, and removed all of the top plate except for that ~42mm wide strip (while still strung and tuned), and the pitch of the strings only dropped about a half tone. It didn't collapse.

.. what connection does static loading have for tone?

Nobody seems to be able to say anything about this.

I have said before and I'll say again:

Bucur shows graphs where static load influences modulus and damping for about a few weeks, until things stabilize.

To first order, static load doesn't have much effect on modes.

However, there could be a frequency drop for curved beams in compression.

I have tested frequecy response of a violin with strings at very low tension, and at full tension, and there has been no significant frequency shift in any of the body modes, so my conclusion is that static stress isn't doing much.

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I have said before and I'll say again:

Bucur shows graphs where static load influences modulus and damping for about a few weeks, until things stabilize.

To first order, static load doesn't have much effect on modes.

However, there could be a frequency drop for curved beams in compression.

I have tested frequecy response of a violin with strings at very low tension, and at full tension, and there has been no significant frequency shift in any of the body modes, so my conclusion is that static stress isn't doing much.

Bocur said; you said that he said it... I don't remember. Nobody has explained what might be a 2nd or higher order mechanism, and I don't mean geometric deformation. I know about the beam under compression. The restoring force becomes less for a sidewas defletion. And this is none-damping. I don't expect much mode frequency change, even if it did some other frequency range might be helped. I am speaking of possible damping.

I don't care about frequency shift of modes. It seems to me that some tensions increase damping or decrease effective coupling of string and violin. Too-tight or loose soundposts come to mind.

I still recall my experiments with a soundpost of variable tension. (A screw threaded through the back and contacting a socket in the top.)

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Nobody seems to be able to say anything about this.

Yes we have said a lot about it but I think you do not like the answers. The changes in frequency response from a fiddle with no strings to one with strings are not large (not easy to compare properly by measurements, though). Responses taken at different string tensions are very small (much easier to get good measurements). This tend to indicate that the tension does not have a large effect on tone.

There are some changes taking place though, like small changes to the arching shape. That does give changes to the frequency response and thus possibly to the perceived tone. Over time the arching may change more due to creep. Oliver Rodgers and Pam Andersson showed by their FEA that arching changes give chnages to the frequency response.

I know you are interested in membrane effects and in plane tension effects on tone from a violin.

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I don't care about frequency shift of modes. It seems to me that some tensions increase damping or decrease effective coupling of string and violin. Too-tight or loose soundposts come to mind.

I still recall my experiments with a soundpost of variable tension. (A screw threaded through the back and contacting a socket in the top.)

I am pretty sure that the arching has changed by that variable tension soundpost. When it comes to any possible effects on damping I now have a fairly fast technique to measure broadband damping in a violin that seem to work. I can compare what damping we get from an unstrung fiddle and a strung up fiddle. However, the strings does add some damping by themselves, especially when they are damped by rubber foam in front of and behind the bridge. The string tension could be loosened while the foam rubber are on and the fiddle could be re measured. Best guess is that not much differences can be seen.

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I am pretty sure that the arching has changed by that variable tension soundpost. When it comes to any possible effects on damping I now have a fairly fast technique to measure broadband damping in a violin that seem to work. I can compare what damping we get from an unstrung fiddle and a strung up fiddle. However, the strings does add some damping by themselves, especially when they are damped by rubber foam in front of and behind the bridge. The string tension could be loosened while the foam rubber are on and the fiddle could be re measured. Best guess is that not much differences can be seen.

You think it is geometrical and you speak of frequency response. I think that regardless of a wide variety of archings, a too-tight soundpost always does the same thing.

And No, I was not satisfied with any answers. I have asked this in several ways to Dr. Woodhouse, and he does not have any good ideas, or so he says. (And he DID understand my questions, which you seem not to. It is not about eigenvalue frequencies.)

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I am saying that my intuition of the effect of tension on the instrument response is likely to be small, and if it has any it is going to be not only on the damping but on the eigenvalues, or the resonance frequencies. If there is no effect on these, there is only a small part of the energy involved in the tension part and it can basically be neglected.

One never know before good measurements or calcuations are done, though. There are in plane components of the vibrations that are important. I think it is impossible to understand the B1 modes e.g. without understanding how e.g. the in plane movements of plate boundaries couple the plates through the ribs.

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