Is this arching wrong ?

[Dr. Mark]

2 hours ago, Andreas Preuss said:

In any case it should be clear to anyone that there will be never a general formula where you feed in basic parameters and it will spit out what you have to watch for when you build the instrument. 

Probably best to pass on unnecessary generalizations - it's hard to say how the future will unfold, don't you think?

[Don Noon]

2 hours ago, Andreas Preuss said:

In any case it should be clear to anyone that there will be never a general formula where you feed in basic parameters and it will spit out what you have to watch for when you build the instrument. 

Most of that has already been done... the "correct" taptones, impedances, and various other specifications.  However, the best makers don't tend to put out that stuff.

[Dennis J]

My intuition tells me that Andreas Preuss might be onto something regarding ribs. There are plenty of scans showing all sorts of deformation such as bulging ribs and buckling which suggest to me that construction weaknesses are not helpful.

 

[LCF]

24 minutes ago, Dennis J said:

My intuition tells me that Andreas Preuss might be onto something regarding ribs. There are plenty of scans showing all sorts of deformation such as bulging ribs and buckling which suggest to me that construction weaknesses are not helpful.

 

200 years under load us a very long time for something like wood which is mildly plastic. Violin like many high performance musical instruments  exists right at the edge of chaos as far as strength is concerned. To make them much stiffer or heavier is to change the way they work. There are direct consequences  eg might as well make the tops really thick so they don't distort over time --- doesn't usually turn out very well!  I think in general they have evolved to the best stiffness to weight ratios possible with the materials used and constrained by the playing requirements.

But, explore, use new materials, innovate!!! See what happens.

[Violadamore]

14 minutes ago, LCF said:

But, explore, use new materials, innovate!!! See what happens.

Besides watching your sales plummet, you mean?  

[LCF]

6 minutes ago, Violadamore said:

Besides watching your sales plummet, you mean?  

Violins which aren't fragile and don't fall apart would also be bad for business.

 

[Dennis J]

Yes LCF I'm sure violins are under a lot of stress and age might not help which seems to me a good reason to build in strength where it is needed. I've had trouble bending ribs which are more that 1.4 or so in thickness but have managed about 1.3, although I am using pretty old rib stock which probably doesn't help. To me thicknesses about 1 mm, which seems to be fairly common, are too thin. So I think 1.2 to even 1.5 in places is about right. While the difference between 1.0 and 1.3 is quite a lot surely weight wise it is not very significant. Similarly a variation in thickness of the top plate between say 2.5 mm and 3.5-4 mm is not going to add a lot of weight to the instrument. I can't see violin plates and ribs, particularly if lower density wood is used, being strong enough

.

[LCF]

3 minutes ago, Dennis J said:

Yes LCF I'm sure violins are under a lot of stress and age might not help which seems to me a good reason to build in strength where it is needed. I've had trouble bending ribs which are more that 1.4 or so in thickness but have managed about 1.3, although I am using pretty old rib stock which probably doesn't help. To me thicknesses about 1 mm, which seems to be fairly common, are too thin. So I think 1.2 to even 1.5 in places is about right. While the difference between 1.0 and 1.3 is quite a lot surely weight wise it is not very significant. Similarly a variation in thickness of the top plate between say 2.5 mm and 3.5-4 mm is not going to add a lot of weight to the instrument. I can't see violin plates and ribs, particularly if lower density wood is used, being strong enough

.

It is amazing that violins last as long as they do although most of the favoured old ones seem to have had major rebuilds and they need regular costly maintenance if they're being played.

A top end wooden clarinet in comparison  might only be expected to last 5-10 years max before being sold on to a student. Not just from changes in wood but from keywork wear and drifting precision. Lets not go down the path of discussing how long cars last :-|

 

I agree with the gist of what you're saying. It seems reasonable. Basic engineering + experience inform us that the stiffness of a 'beam', an object subject to bending forces, is proportional to its elastic strength X width X ( thickness cubed) It is non-linear in the thickness so the stiffness of a rib which is only 25% thicker say 1.25 vs 1.0mm is nearly doubled. Same as 1.5 vs 1.2mm. That is an octave increase in the stiffness rather than proportional and as you say not as much gain in the mass. 

 

What if the acoustic outcome depends on the stiffness? Probably more likely on a top where an increase from 2.5 to 3.5 leads to an increase of 2.7 times stiffness ~an octave plus a fourth.

Does that matter? 

 

However wrt some Strad, Guarnerius etc, one doesn't know what the Mantegazza Bros were really up to!!!

[Dennis J]

I have always had the feeling that the structural integrity of a well built violin under string tension should be more responsive than one which may in some way have collapsed either because of age or weakness in their construction. Newer violins, made properly, should be superior to the very old ones out there.

What you are saying suggests to me that fairly small thickness variations of tops might be quite consequential. As far as ribs are concerned I think that once they get to about 1 mm they tend to lose shape anyway.

 

[LCF]

3 hours ago, Dennis J said:

What you are saying suggests to me that fairly small thickness variations of tops might be quite consequential.

 

I'm sure of it. But I certainly don't know what those consequences exactly are. My understanding of 'the violin problem', the valiant quest for a unified theory related to what Don mentioned up above, is that this is a multidimensional problem where there are consequences of everything you do but those are not always ( searching for a word  )  homologous, to what you did. 

Eg something as significant as thinning the central area of the top has a lot of consequences. This is exactly the things that Anders Buen lists in his big spreadsheet, statistical connections between eg signature modes and final outcomes, and other stuff. 

What Don said.

What Anders said. 

 

Fathomables.

 

 

[reguz]

Hello.

It seems to me that you think I know more about how your instruments work than you do yourselves,

That is by no means the case.

What I am giving you information about is what I have come to through many years of work and thinking.

So, it has nothing to do with any of your instruments. It should have been clear.

What you yourselves have had the opportunity to compare by examining your instruments structure, I know nothing about that. Dop you? As far as I know, you have never provided any information about this.

You recently received documents to read how I worked and what it has led to.

I have done friendly but none of you have responded with what you have come up with yourself.

By that I mean that it is documented with a drawing or similar.

Of course, you can criticize the material I show quite openly, but you don't, instead you express yourself in a way that I didn't expect.

I am completely open about what my research has come up with and still have a lot to tell.

Among other things is that I know how I  can influence and increase tension in the belly without doing anything to the belly itselve.

I think everyone must have understood that the tension on the belly affects the sound outcome.

How and where it happens has been for me to understand so that I can influence the result thus not oly by moving the sound post.

Remember that early Luthiers did not have the slightest technical knowledge that we have today.

Thus, first of all try to think at that level then you might possible find an answer.

It requires great humility when faced with solving a problem.

Jacob Saunders recently wrote;

The nice thing about violins, is that the exact physics of how and why it works have always been mysterious. For centuries there have always been no end of egg-heads, queuing up to explain everything to perfection, and one may ignore them all, since they only make fools of themselves

I have been trying to find the answer to how one construction can work but so far have had to endure a lot of negativities from you. It would be much better to cooperate.

I have had a lot of questions confirmed and feel that I am on the right track to a good understanding of how the construction I use works in theory and in practice.

I wish you all a Merry Christmas

[Andreas Preuss]

9 hours ago, Dennis J said:

My intuition tells me that Andreas Preuss might be onto something regarding ribs. There are plenty of scans showing all sorts of deformation such as bulging ribs and buckling which suggest to me that construction weaknesses are not helpful.

 

That’s a theme I am now a sort of addicted to. 
 

The first thing I tried (already 5 years ago) was to save weight at parts where I thought that they don’t matter too much for the sound, so first of all the ribs and then the whole neck. 

What came clear is that paper thin ribs absolutely kill the sound of otherwise normally built top and back. (And I am sure this accounts for EVERY violin) My interpretation of this is pretty simple. The parameters of the single plates such as arching, graduation and total weight are secondary to the stiffness of the ribs. Otherwise it would be possible to counterbalance weak ribs with whatever you can manipulate on top and back. You could also say all parameters to adjust top and back to each other or calculate certain arching patterns are meaningless without the right rib construction.
This means the construction of the ribs governs the construction of top and back. When correcting the paper thin ribs to improve the sound, some fundamental improvement steps could be made, improvements by far more clear than any efforts on regraduations, bass bar, and other means we usually consider for sound adjustments.

So to me the classical concept hits the borders of its possibilities because of the rib construction. Furthermore it is interesting to note that acoustic research with marginal exceptions largely ignored the influence of the rib construction on the sound.

 

[fscotte]

Violins last a long time obviously because of the way they're constructed, which has been fine-tuned over hundreds of years I suppose.

Think about how delicate an egg is.  However if you tried to squeeze an egg with all four fingers in the palm of your hand, you cannot break it. Something similar happens with a violin body. All the forces that push are counteracted by the arching.

[Andreas Preuss]

4 hours ago, reguz said:

I wish you all a Merry Christmas

Merry Christmas, Robert.

[Andreas Preuss]

6 minutes ago, fscotte said:

All the forces that push are counteracted by the arching.

Not quite. There are quite many Cremonese instruments which suffer from a sunken-in top plate. (Or pulled up end blocks, depending how you see it.)

[Dr. Mark]

4 hours ago, reguz said:

I wish you all a Merry Christmas

and a Merry Christmas to you as well.

[Violadamore]

5 hours ago, reguz said:

I wish you all a Merry Christmas

Now, that I can agree with.  Merry Christmas!  

[sospiri]

4 hours ago, Andreas Preuss said:

That’s a theme I am now a sort of addicted to. 
 

The first thing I tried (already 5 years ago) was to save weight at parts where I thought that they don’t matter too much for the sound, so first of all the ribs and then the whole neck. 

What came clear is that paper thin ribs absolutely kill the sound of otherwise normally built top and back. (And I am sure this accounts for EVERY violin) My interpretation of this is pretty simple. The parameters of the single plates such as arching, graduation and total weight are secondary to the stiffness of the ribs. Otherwise it would be possible to counterbalance weak ribs with whatever you can manipulate on top and back. You could also say all parameters to adjust top and back to each other or calculate certain arching patterns are meaningless without the right rib construction.
This means the construction of the ribs governs the construction of top and back. When correcting the paper thin ribs to improve the sound, some fundamental improvement steps could be made, improvements by far more clear than any efforts on regraduations, bass bar, and other means we usually consider for sound adjustments.

So to me the classical concept hits the borders of its possibilities because of the rib construction. Furthermore it is interesting to note that acoustic research with marginal exceptions largely ignored the influence of the rib construction on the sound.

 

But Stradivari's ribs are very thin with wide tapered linings. He did this for a reason. Not just to make the ribs easier to bend. The violin is distorting laterally when it's played.

So thin ribs with wide tapered linings allow more freedom of movement without sacrificing structural integrity.

14 hours ago, Dennis J said:

My intuition tells me that Andreas Preuss might be onto something regarding ribs. There are plenty of scans showing all sorts of deformation such as bulging ribs and buckling which suggest to me that construction weaknesses are not helpful.

 

Isn't the reason why the ribs are bulging on old instruments is because the plates have shrunk slightly across the grain?

[HoGo]

23 hours ago, Don Noon said:

Everything is squishy.

Perhaps except one person in this thread.

[Marty Kasprzyk]

4 hours ago, Andreas Preuss said:

 

So to me the classical concept hits the borders of its possibilities because of the rib construction. Furthermore it is interesting to note that acoustic research with marginal exceptions largely ignored the influence of the rib construction on the sound.

 

Thinning the ribs or using a lower elastic modulus reduces the various body mode vibration frequencies.  This might be helpful or harmful depending upon what instrument is of interest.  For example low body frequencies are frequenty helpful for violas or cellos where the intent is to produce low pitch notes with instruments which are relatively too small compared to the wave lengths of sounds they produce.  

If the ribs are too thick the instrument may sound too bright or harsh.  I watched a good maker/shop owner tediously scraping the inside surface of a cello he couldn't sell because it didn't have a deep enough sound character.

On the other hand some violins might not be bright enough because the ribs are too thin.  Violins might benefit from using thicker ribs but thick ribs are difficult to bend into shape.

Furthermore it is interesting to note that acoustic research (attached) showing this influence of the rib construction on the sound has been largely ignored by makers with marginal exceptions.

JASA 2015 Shell modes(1).pdf

[Peter K-G]

Linings are covering half of the ribs

[reguz]

Dear Marty. Did you study how C Gough constructed the instrument? There is no scoop shape and the belly shape with cross over radii has chord line on the outline. There neither is lining on the rib that follow the instrument rib inner line. I had long discussion with C Gough about this "instrument" and how he handled it making the Mode shape condition. I cannot learn much at all from this long report. Of course, C Gough make no calculation faults. The result is based on the input data. I hope any of you can make us of what is shown in the report.

[reguz]

5 hours ago, Andreas Preuss said:

Not quite. There are quite many Cremonese instruments which suffer from a sunken-in top plate. (Or pulled up end blocks, depending how you see it.)

Andreas, that is what I hoped to discuss so we get a clear answer what it is. Two actions in relation to ONE or One action in relation to TWO. it’s the string acting at two location that produces the result. If you sit in your car and start driving. You can say it’s the road move under the car backward while most of us say we are going forward.

Yes, is it how you see it?

[violinsRus]

Back to the original poster's question, here's an old Viennese with full arching, and a thin belly plate.  It has lovely tone, in spite of the extensive repairs.  I find the arching works very well on this 18th century instrument.

 

[David Burgess]

9 hours ago, Andreas Preuss said:

Not quite. There are quite many Cremonese instruments which suffer from a sunken-in top plate. (Or pulled up end blocks, depending how you see it.)

 

3 hours ago, reguz said:

Andreas, that is what I hoped to discuss so we get a clear answer what it is.

Regus, there is no single clear answer. It is only you who seems to be obsessed with the notion that there is.

All depends on which point one chooses as their stationary point of reference. Most makers choose a different one than you do, possibly because moving endpoints seem to radiate a lot less sound than more central moving areas. Deal with it, and maybe learn a little something from it, if such a thing is possible for you.