David Beard

Have we caught the rabbit yet? Are we making stew?

The essence of their cultural evolution and success is that none of them started over. They all stuck to tinker with different combinations of traditional choices, reuses of traditional choices, and occasionally small extensions. It was a VERY conservative process. With the geometry choices, we have the advantage of being able to see them fairly directly and completely. And you can look at their choices and compare from instrument to instrument. Stradivari wasn't some renegade reworking the system. He mostly made just slightly different combinations of the same choices you can observe being used in other earlier making. He did quite a bit of returning to Andrea Amati. Much more than being innovative, he was just probing and effective. As with the evaluations and directions of exploration, I agree isn't wasn't all just sound/playing evaluation. Strad particular seem to explore refinements of choice aiming for the visual. But also, it seems they pursued 'notions' to some extent. This is very clearly evident in Del Gesu foe instance. He for example pursued elongating the extension of the soundhole shape above and below the eyes. And, as you pointed out, Strad pursued flatter top arches rather more than had been done.

Remember, the Northern Italians already ran a continous series of these trail and evaluation experiments, for over 5 centuries. They carried this on from late medieval times until the early phases of the industrial revolution disrupted the continuity of their making tradition. Across countless iterations of bowed and plucked lute type stringed instruments, they explored differing choice in the making, and evaluated results the way you describe. Not by knowing why something they tried worked, but by deciding if it work. By judging results by eye and ear rather than good or bad theory. And, they essentially encoded their learning in traditions of preferred geometry and proportion choices. All of their centuries of collective learning informed the violin, leading to its peak of success in the preferred traditional geometry choices of late Cremona makers like Strad and Del Gesu. Like others, I also enjoy enjoy trying to understand why violins behave as they do. But this is a very separate curiousity from seeking to know how to build good violins. Consider some of the more definite experimental results from this thread. We have for example the concrete results that both a too thick top and a too light treatment of linings/edges are bad. But the examples of the old masters already told us not to do those things. Scratching the itch to understand is one thing. But to improve our making, it's probably much more efficient to focus on learning the ways of the old masters. Their traditions of structured geometry choices embed over 5 centuries of collective learning from trial and aesthetic evaluation tinkering and exploring.

This is very wrong headed.

I think this is the exception to my point. The extra strength in the linings, particular through the cBouts, helps make the top in comparison more flexibly or independently movable. My point was more that many of the shaped elements, like the center back mass, the archings, the bar, the post, even the way the soundholes cuts up the plate, these are about enabling certain modes of vibrations, but lower ones. The freedom and strength of higher frequencies depends mostly on just a few specific aspects of the instrument. I think these include sufficient thinness in the top plate and the 'daiphragm' parts of the back, thinness in the actual ribs, contrasting 'out of plane' strength in the sides from the working of linings and edges and approach to edges, and on the bridge table and it's relationship to post bar and bridge. There could be other specific factors. But these are the ones I see so far.

A things come to mind. Most of all, as others have said in this thread already, the strings themselves and player are the source of the high overtones. So that implies that the violin's job is not to create those formant high tones, but to give them a place to build energy and then radiate as strong component of the 'signal'. The other thing is that these higher frequencies components correspond to a patchwork of physically short standing waves in the plate, and a patchwork of physically smallish air volumes in the air body. This suggests that larger scale design elements like the bar and the arching would be comparatively less significant for these frequencies. But a big factor would be comparatively thin and flexible plates that can readily break up into a patchwork of driven standing waves. But the plates need to balance this by also being thick enough to move in more unified ways for lower modes of vibration.

I mostly use red willow from Rivolta. Completely happy with this.

I think I'm seeing. Seems I have some bogus notions floating around in my thoughts about springs and oscillation.

That can't be a complete picture. If I take a spring that barely begins to stretch with 10lb load, say it stretch 5mm. And, if I pair this with another spring that stretches say 60mm with an 8ounce load. Well, if I trap something of negligible weight between these, the lighter spring will only barely be able to engage the heavier spring. You will be technically correct. But the combined system will behavior very much as the unloaded heavier spring would. That is that light pulls on the trapped object would only barely stretch. I guess the core intuition of my earlier suggestion, that part that is either right or perhaps wrong, is the intuition that if you trap something between two of the heavy springs, and then stretch them a total 60mm, it should now take less than 10lbs force to move the trapped object 5mm. Hmmm?

Just thinking about coiled metal springs as an analogy for other systems of mechanical oscillations, obviously there are physical boundaries to free oscillation behaviors, and related driven behaviors. The conditions for free oscillation of a weight hanging from the string in two points. 1) the spring must be sufficiently load to stretch. 2) the load must not overwhelm or break or plastically deform the spring. These can reduce to one condition that the spring and the mass reasonable balance each other. It seems possible to me that both the string tension and the post tension may need to be rather high to load the twisting of the treble side bridge table and allow that dynamic to act as an admittance path for high frequencies as deflections of the plate. Also, a spring loaded by a free weight is not as good an analogy for this twisted bridge table analogy as would be something trapped between two oppossing springs that are loaded by stretching. In this analogy, the weight of the trapped something is not necessarily a primary factor. And, in fact, the something could be more of transmission point than the main thing being oscillated or driven. It could even be something like a transmission lever. But, the interesting thing here is that a close good balance between the opposing springs would greatly contribute to the freedom in this kind of system. Perhaps that is what's happening, why the tensions matter. The twisting dynamic is present at all until you introduce the opposition of the post and loaded bridge foot. And, the dynamic isn't basically free unless the post tension and string tension are both sufficient. And, the dynamic isn't very very free until the tensions find a good balance. It's an idea. And at least it roughly confirms to setup experiences.

Ok. I think I get the point. As long as the static load is enough to preengage all the material flexes involved, and not so much as to crush or overwhelm any of the flexures, then the amount of load doesn't change material stiffnesses or the system in that way. However, intuitively something stills seems wrong in this. It seems like the tension of the post setting matters greatly in terms of practical results. But how can this tension be important but the string tension not be important. That's confusing.

What I'm mostly think of is the twist of the bridge island by the post pushing up and the treble bridge foot pushing down. The downward push of the bridge foot is almost entirely from the strings. Changes in this little twist seem likely to be the quickest and therefore the highest frequency movements of the top.

Maybe I'm wrong. Won't the cantilevered twisting relationship between the post, treble bridge foot, and the treble area of the bridge foot change?

I'm not so sure for a driven system that string tension is quite so irrelevant? I suspect the post and bar, in relation to the bridge feet and string tension serve as a sort of crossover system that is quite sensitive to the string tension. For some frequencies, the post will look immovable, and for other frequencies it will look movable. Same with the bar. The frequencies that can move the post and bar I suspect will change with a large change in string tension. And, these things will change the balance of frequencies and energy that travel certain physical paths and drive certain parts of the violin and it's response.

I think basically so. I believe electrical theory includes the notion that energy will take the easiest path. And I think a similar thing happens with vibrations. But with vibrations, it seems to be frequency dependent. High frequencies and high noose seem very ready to roll around in anything that kinda of presents as a stiff shell. Lower frequencies want to setup as standing waves, either at a natural resonance frequencies, or driven at a frequency not too far from a resonance. But it seems to take a bit more energy for these lower waves to set up. When that doesn't happen, energy seems to readily go instead to higher harmonics and high noise.