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long arch


yapkv
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I was playing with carmetal again, now on GDG's Kreisler 1730 long arches, using image downloaded from Library of Congress

post-5067-1270070364.png

seems to me the back arch is an arc of a circle. the upper and lower parts of the top arch are both arc of smaller circle. The middle of the top arch seems to be a flatter arc.

here is a zoom-in diagram... the arcs seems to fit quite well.

post-5067-1270070408.png

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Hmmm, you've done just what I have been meaning to do some day here... So, having taken it this far my question is, if you take the radii (or perhaps the foci of the circles), how does such tie into the Golden Section? Lately, I have been OBSESSED with the Golden Section and the Fibonacci sequence, and realizing that some of this applies to the form of the violin, I was just wondering if anyone has found a relationship with regard to the long arch (as well as the cross arches, the manner in which they vary along the length of the instrument).

With regard to the "plateau", this is forever a question, it seems. I used to think it was due to distortion over time (and perhaps this is the case here and there, now and then), but I no longer feel as though such is the case with regard to the likes of what we have here (the Kreisler del Gesu). And then there's always the matter of the later del Gesu's, and their lack of a plateau (the Ole Bull, the Leduc, etc). They're another mystery altogether, however a VERY important one when considering the topic of this post!

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To create a Circular arc passing through 3 points:

A straight edge thru points 1 and 2

A straight edge thru points 2 and 3

Two nails to hold the two straight edges together,

preserving the angle.

slide the angle back and forth on points 1 and 3 (nails)

The intersection moves along a circle that passes thru

1, 2 and 3. A simple way to trace a large diameter arc

in a small space.

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seems to me the back arch is an arc of a circle. the upper and lower parts of the top arch are both arc of smaller circle.

post-5067-1270070408.png

Excellent work! What is the relative length of the chord and what is the relative length of the radius. From that ratio we can calculate the actual radius. Is it close to 110 cm?

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I was playing with carmetal again, now on GDG's Kreisler 1730 long arches, using image downloaded from Library of Congress

I am sorry if this is taken the wrong way but it really isn't possible to take the radius of an old violin. You have to consider the dramatic changes that have occured over nearly 300 years. Look at Melvin's and Michael Darnton's notes about long arches. Both have approaches that are sound. My approach is a little different but it not based on present morphology. My approach is somewhat theoretical but not vastly different than what Michael or Melvin end up with.

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(from yapkv's pics)

I got a back radius of approx. 511mm

with a back length of approx. 179mm

so, your 110cm was referring to what ?

radius, no.

diameter approx 102.2 cm

how does your 110 relate ???

E.

Well, I just open the image in Photoshop and measured the chord and the radius. The chord measured 15 cm and the radius measured 48.4 cm. That ratio: radius / chord is 3.27. If a standard violin is around 354 mm the chord part is in a bit from each end so I estimate it to be about 330 mm. Multiply that by 3.27 to get 1064.8 mm which is pretty close to 110 cm estimate.

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With regard to the "plateau", this is forever a question, it seems. I used to think it was due to distortion over time (and perhaps this is the case here and there, now and then), but I no longer feel as though such is the case with regard to the likes of what we have here (the Kreisler del Gesu). And then there's always the matter of the later del Gesu's, and their lack of a plateau (the Ole Bull, the Leduc, etc). They're another mystery altogether, however a VERY important one when considering the topic of this post!
The plateau is of particular interest to me, as the maker I learned from was self-taught. He would actually make the plateau dead flat along the long arch. Unless you pointed this out, most people wouldn't even notice this as it melded in with the radius on the top and bottom. He made many successful instruments based on this type of long arch.

I can't help but wonder if he knew something more than what I thought he did. He built about six or seven hundred instruments in his lifetime, so perhaps he arrived at some empirical method by accident.

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The plateau is of particular interest to me, as the maker I learned from was self-taught. He would actually make the plateau dead flat along the long arch. Unless you pointed this out, most people wouldn't even notice this as it melded in with the radius on the top and bottom. He made many successful instruments based on this type of long arch.

I can't help but wonder if he knew something more than what I thought he did. He built about six or seven hundred instruments in his lifetime, so perhaps he arrived at some empirical method by accident.

I think you may find this idea e.g. in Otto, and maybe Max, Möckels violin making books from the 30ties too. A flat region of the long arch of the top and a back arch at it highest at the soundpost position, I think.

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Hi everyone,

Just to add to the fun, here are some shots of the long arch (top and back) of two violins that came through the shop for new bridges today. The first two are Antonio Stradivari c.1710 and the second two are Guarneri del Gesù c.174.... .

The Stradivari is pretty straight and the back is in excellent shape, the top may have been corrected (pushed up) in the central area. The Guarneri rib garland is not very straight and I had a hard time trying to line things up for the camera. The top on the Guarneri has a slight "cupid's bow" deformation in the bridge area which is to be expected. The instruments are tuned up to pitch which changes the shapes.

Sorry about the so so photographs, I had very little time for this. :)

Bruce

post-29446-1270151145.jpg post-29446-1270151162.jpgpost-29446-1270151267.jpg post-29446-1270151354.jpg

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Thanks, Bruce. As usual, very interesting photos. Really is an amazing rib-line on the del Gesu. Plus so much else to look at.

That's without even going into what it must be like to have two such violins come into "the shop for new bridges today." ! :)

Appreciate the photos.

Cheers,

Ken

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Thanks, Bruce. As usual, very interesting photos. Really is an amazing rib-line on the del Gesu. Plus so much else to look at.

That's without even going into what it must be like to have two such violins come into "the shop for new bridges today." ! :)

Appreciate the photos.

Cheers,

Ken

Hi Ken,

Yeah, but they're always "in and out". There never seems to be enough time to sit down in peace and quiet and study the darn things. Being a "late" Guarneri I don't know if the ribs were ever really straight.

Bruce

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Hi Bruce:

Echoing Ken's sentiments may I ask how liability issues for such treasures are handled by shops? Does the player's insurance cover shop time or do you have to have coverage equal to the value of each instrument too in case a disaster occurs while under your care and control?

Fascinating stuff...

Ernie

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here are some shots of the long arch (top and back) of two violins that came through the shop for new bridges today. The first two are Antonio Stradivari c.1710 and the second two are Guarneri del Gesù c.174.... .

Bruce

Fascinating - the saddle on the GdG looks very high. Is that real or an optical illusion?

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The instruments are tuned up to pitch which changes the shapes.

Bruce,

Those are great photos.

It looks like the top arches of the Strad and del Gesu have a somewhat long plateau and slight dip, respectively, in the middle sections, while the backs of both form continuous curves with no flat spots or dips (ignoring channel areas). Just looking at what's there now under tension, the differences between tops and backs seem strong enough that one might think very different concepts were used to come up with top arch vs back arch.

Would the differences between top and back archings be diminished enough if the fiddle strings were off to believe the same concept was used for both top and back archings? If one could imagine undoing the effects of time, would the top and back archings be similar enough to believe the same concept was used for top and back? In short, do you believe that the same concept was used for top and back archings?

As always, thanks for any reply.

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the saddle on the GdG looks very high.

There's a lot more room between bottom surface of fingerboard and the top of the del Gesu than in the Strad, too. I'm assuming there's a higher overstand in the del Gesu than in the Strad. Maybe a higher overstand and saddle allow for a taller bridge on the del Gesu without creating steeper string angles at the bridge.

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Hi Bruce:

Echoing Ken's sentiments may I ask how liability issues for such treasures are handled by shops? Does the player's insurance cover shop time or do you have to have coverage equal to the value of each instrument too in case a disaster occurs while under your care and control?

Fascinating stuff...

Ernie

We have our own insurance but if we go outside our normal level of coverage then we have it raised by the insurance company temporarily. This keeps the premiums down to a reasonable level.

Most insurance policies do not cover damage directly caused by repairs but they do cover accidental damage, theft, fire etc.

Bruce

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Hello Bruce,

amazing pics, thank you! And I like the casual "two violins that came through the shop for new bridges today" :)

The long arch of the back of the DG seems to be quite concave in the upper bout, especially when compared with the Strad which appears very full to upper block. Is my interpretation correct?

Thanks again,

Roland

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If one could imagine undoing the effects of time, would the top and back archings be similar enough to believe the same concept was used for top and back? In short, do you believe that the same concept was used for top and back archings?

I think it's a question without solid answers, until we perfect time travel. What's fair to say is that top and back archings would have been much more similar than we see them today. If one follows almost any instrument for 20 years, one can observe the top becoming more plateaued, with increased bulging in the upper and lower bouts. The deformation seems to be most extreme on thin instruments without a hard, brittle varnish, and is accelerated by exposure to high humidity and humidity fluctuations. There are also some typical arching deformation artifacts from repeated clamping of a top with the old-style spool clamps, and the way plaster molds were often used to correct arching (it's easier to remove plaster than to add it).

I've posted this before, but this is a picture of a template which was made to fit a top, compared with the same top 25 years later. This isn't intended to be a substitute for an answer from Bruce. I too am interested in his thoughts on how similar top and back archings might have been originally.

archingdistort.jpg

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The late del Gesu's (and at least one late Strad of which I am aware) keep making me think the plateau, while sometimes perhaps a result of distortion over time, is not always the case. The more I think about it, the more I think it is deliberate (most of the time). Also, Michael has mentioned elsewhere (the words lodged in my brain), that the outer form he realizes (or has as of recent times) results in an instrument that distorts remarkably little over time, often keeping the same soundpost as originally fitted. Michael, if I am mis-quoting you here, even if somewhat loosely, correct me, but this is what I recall. I also recall, from some time past, the comment that a flattened center region results in an instrument more open and responsive (all else being kept equal).

In my opinion (yes, opinion), arching is to utterly critical to the final tonal result, so I tend to think about it a lot. Plus, it is a great aesthetic, so how can one help but focus in on the nature (and ponder the origin of) those lovely shapes? For those of you who may have missed it, here's another, recent post with some pretty decent insights:

http://www.maestronet.com/forum/index.php?showtopic=321351

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Hi everyone,

Just to add to the fun, here are some shots of the long arch (top and back) of two violins that came through the shop for new bridges today. The first two are Antonio Stradivari c.1710 and the second two are Guarneri del Gesù c.174.... .

The Stradivari is pretty straight and the back is in excellent shape, the top may have been corrected (pushed up) in the central area. The Guarneri rib garland is not very straight and I had a hard time trying to line things up for the camera. The top on the Guarneri has a slight "cupid's bow" deformation in the bridge area which is to be expected. The instruments are tuned up to pitch which changes the shapes.

Sorry about the so so photographs, I had very little time for this. :)

Bruce

post-29446-1270151145.jpg post-29446-1270151162.jpgpost-29446-1270151267.jpg post-29446-1270151354.jpg

Bruce, thank you for taking the time to share these with the rest of us (who have yet to handle the subject matter in so direct a manner!). Thank you. I agree the cupid effect you mention is distortion (at least I hope it is, because like Mike I want to believe). I would guess the instrument began life with something of a plateau (rather than a valley, or depression), and as for restorative effects (arches pushed up and the like)...whew, talk about muddying the waters!!!

But, as important and something we all need to remember here, is that while the human hand-eye system is capable of amazing feats of accomplishment (being able to discern very, very minor variations), these intruments are the result of work completed by hand, in a real-life shop, with economic burden (in addition to various other burdens in life, of all manner and sorts). So, we ought not read too much into each and every example, but rather take stock in trends that hint at what may have been a system, a goal, the "method behind the madness". This requires a lot of observation (more than I've been gifted), and the ability to gaze upon the forest from a distance, so as to not become lost among the trees.

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