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Block height, rib taper


Lafont
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I'm no expert, but I could never be bothered with tapering the ribs; I have yet to see any real benefit for doing so.

One of the most obvious benefits of tapering the ribs from the treble side is an increase in the angle of the strings over the bridge without actually making the bridge any taller. Looking at the bridges, bridge patterns, and fingerboard alignment bridges from the Museo Stradivariano they appear to be on the short side compared to modern set up( Roger H may have a differing opinion on this). Violin bridge (MS no 143 = 28mm), fingerboard alignment/projection bridge (MS no 147 = 22mm). The extra angle would have been helpful to the sound.

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One of the most obvious benefits of tapering the ribs from the treble side is an increase in the angle of the strings over the bridge without actually making the bridge any taller. Looking at the bridges, bridge patterns, and fingerboard alignment bridges from the Museo Stradivariano they appear to be on the short side compared to modern set up( Roger H may have a differing opinion on this). Violin bridge (MS no 143 = 28mm), fingerboard alignment/projection bridge (MS no 147 = 22mm). The extra angle would have been helpful to the sound.

You are right!

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I thought I remember reading in Roger's writings about this taper that it is unclear whether the taper was applied to the back or top of the rib cage.

 

If it was applied to the back... like in the dramatic way it is done on the bass... there would be no increase in angle of the strings over the bridge?

 

E

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I don't quite follow what you are saying. Are you indicating the neck overstand is lowered and the neck angled back more in conjunction with the lowered top block / belly? Why would the slight increased angle be beneficial to sound production?

Yes, the neck is set in the upper block. The over stand is measured from the upper block. If the upper block is lower than the other blocks then the neck is also lower by the same amount.

The angle of the strings over the bridge provides a certain amount of load to the instrument. It also has a strong effect on the upper harmonics. The greater the angle the more the upper harmonics will be amplified and the brighter the instrument will be.

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I thought I remember reading in Roger's writings about this taper that it is unclear whether the taper was applied to the back or top of the rib cage.

 

If it was applied to the back... like in the dramatic way it is done on the bass... there would be no increase in angle of the strings over the bridge?

 

E

Roger conjectures that the taper was applied to the upper surface (top side) of the rib structure.

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Roger conjectures that the taper was applied to the upper surface (top side) of the rib structure.

The difference with the bass back and gamba family instruments is that the backs are canted and "broken" over the cant. A wedged cut is made at the "break" (cant) and the back is hinged or folded over the angle. There is no tension in the back or rib structure.

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No,Because the rib is curved the tapper will not be consistant when it is laid flat. The whole surface of the ribs needs to be trued up anyhow. Someone here, also mentioned using a graduated curve , as opposesd to a simple bend at the uppercorner blocks . I have been using this idea. 

hmmm   After trying to visualize that and experimenting with a curved strip of paper, I had to resort to wolfram for an over simplification to a cylinder,  the recurve of the corners would be an added complication. 

ttp://mathworld.wolfram.com/CylindricalSegment.html

Those formulas give me a headache but I like the drawings :D

 

What do you mean by a graduated curve at the upper corner blocks?

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Yes, the neck is set in the upper block. The over stand is measured from the upper block. If the upper block is lower than the other blocks then the neck is also lower by the same amount.

The angle of the strings over the bridge provides a certain amount of load to the instrument. It also has a strong effect on the upper harmonics. The greater the angle the more the upper harmonics will be amplified and the brighter the instrument will be.

If this is indeed the case, then tapering from the bottom block all the way to the top block instead of just the upper bouts should yield the same result without bending and stressing the belly.

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No, it is the relative height difference between the bridge and upper block. If you taper evenly from one end to the other the bridge will be a little lower than just tapering from the upper corner blocks to upper block.

My explanation is not the only possible reason and not even an explanation of why the Cremonese did it. They may be and probably are many reasons.

I think Bruce's idea of balancing volume of upper an lower bouts is as good as any, too.

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One of the most obvious benefits of tapering the ribs from the treble side is an increase in the angle of the strings over the bridge without actually making the bridge any taller. Looking at the bridges, bridge patterns, and fingerboard alignment bridges from the Museo Stradivariano they appear to be on the short side compared to modern set up( Roger H may have a differing opinion on this). Violin bridge (MS no 143 = 28mm), fingerboard alignment/projection bridge (MS no 147 = 22mm). The extra angle would have been helpful to the sound.

I don't see much accounting for these low bridges when I read various writings on period set up. Does any one have something to say about them?

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hmmm   After trying to visualize that and experimenting with a curved strip of paper, I had to resort to wolfram for an over simplification to a cylinder,  the recurve of the corners would be an added complication. 

ttp://mathworld.wolfram.com/CylindricalSegment.html

Those formulas give me a headache but I like the drawings :D

 

What do you mean by a graduated curve at the upper corner blocks?

I

 Sorry if my terminology is not clear ...I make it up as I go!... by graduated ,I'm sugesting a curve ,so that if the ribs are laid on a flat surface there will be a smooth transtion from the flat with upper, lower corner blocks contacting ,as I push the top block down to the plate  I'm looking for a "role" or gradual progrestion to the upper block as opposed to a click, as it would be if the taper existist in a flat plane , like with the Gambas just described.

  Similar to springing a bass bar, where one looks for no "HOT SPOTS" in the curve just a nice smooth fair curve.

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I

 Sorry if my terminology is not clear ...I make it up as I go!... by graduated ,I'm sugesting a curve ,so that if the ribs are laid on a flat surface there will be a smooth transtion from the flat with upper, lower corner blocks contacting ,as I push the top block down to the plate  I'm looking for a "role" or gradual progrestion to the upper block as opposed to a click, as it would be if the taper existist in a flat plane , like with the Gambas just described.

  Similar to springing a bass bar, where one looks for no "HOT SPOTS" in the curve just a nice smooth fair curve.

ah ok now I understand what you meant by that

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 Thinking about the barouqe string angle and the the built in tension kind of hurts my head. I have only built 3 violins so  far and could'nt imagine leaving the ribs the same height all around. It's such an beautiful detail.

 

 I built a couple of guitars before making violins and they have pronounced taper from top block to bottom block. 

 

 I dont know anything about Strads guitars but I wonder if they have tapered ribs and I wonder if it was a tradition in the lute buisness before Strad started building.

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Just answered the question about Karl Roy's appendices2  in another thread, which gave a fingerboard thickness.

Also written in appendices2, on page 2 under the title of Fingerboard is:

 

the "projection (at bridge)" of 27 mm and .......

"ht over belly at bridge end" 

 

16.5 mm for 1/4 sized instrument

17 mm for 1/2 sized instrument

19.5 mm for 3/4 sized instrument

20 mm for 7/8 sized instrument

 

and finally ...

21 mm for 4/4 sized instrument.

 

Stradivari made all different types and sized instruments, so a well equipped shop would have numerous sized guides.

Yes, he did make all sorts of instruments. But these particular bridges and mock bridges are clearly marked in Stradivari's handwriting as to which instrument model they go with and sometimes their purpose is explicitly stated.

I will look them up in the catalogue later today and give you specific MS numbers.

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I suppose the cbouts aren't damaged because the bridge curve is flatter and the strings wider spaced on the celli at least. Also the height of the bridge is not all that significant in itself. The angle of the strings is what counts and the lower overstand helps to compensate even with a smaller neck angle.

Mark Caudle

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I suppose the cbouts aren't damaged because the bridge curve is flatter and the strings wider spaced on the celli at least. Also the height of the bridge is not all that significant in itself. The angle of the strings is what counts and the lower overstand helps to compensate even with a smaller neck angle.

Mark Caudle

Yes, the bridge curves were probably flatter. That can certainly be checked against the existing templates.

Yes, it is the string angle that is more important. That was the point of my original post (#52). Lowering the upper block helps create more angle of the strings over the bridge. This is especially helpful when you have a bridge considerably lower than a modern bridge.

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For instance:

MS #287 is a "facsimile of a bridge made in willow". W=101mm, H=59mm. Written on it in the handwriting of Stradivari "B Musura per scodere la corda-Bono 1709". Sacconi states it was used to align the fingerboard and set the correct inclination.

The B most likely stands for the B form cello. (It is highly improbable that this is for a smaller cello as the width is 101mm).

If these numbers are correct then projection of the neck on the B form (Duport, Batta,Piatti etc) was a full 20mm lower than modern set up.

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