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 Individual string tension is different from downward force, and I have read violins have the most of the latter but can't remember the source. I mis-wrote when I called downward force tension, since I meant that I read violins have more downward force to the bridge.

Like Don said, downforce can be calculated from string tension, and angle over the bridge. If you wanted to use something like a fish scale to lift individual strings slightly off the bridge, that would get you pretty close too.

 

Just using rough numbers, we have a total string tension of about 50 lbs. on a violin , and an an angle over the bridge of about 20 degrees (compared to a string that is straight, calling that 0 degrees).

 

On cello, we have a total string tension closer to 125 pounds, so even if the angle over the bridge was the same, we'd have about 2.5 times the downforce, or about 42 pounds. However, the angle over the bridge is generally quite a bit higher on cellos, so that makes the downforce even higher.

 

Again, these numbers are very rough, in an attempt to keep the explanation simple.

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Thanks, scientific minds. I guess I just misremembered, which is not shocking because whatever I know, it's very often in the vacuum of not having experience doing the thing. But...string tension on violas is the same and often less than violins. So that's interesting. Probably some information there about how viola grads and archings 'should' be. Though anything goes on violas, more or less.

Thanks for the charts and ideas. I definitely wonder what the effect really is of changing the downward force, because I just imagine the instrument would be less loud. ??? But that's not what some find to be true. Don should play with that, or anyone with the technology. Then post helpful charts for the benefit of lazy people. Sounds like a great idea to me!

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Not Telling,

This is in no way scientific, and I invite everyone to contribute if their experiences conflict with mine, but my experience with changing the string angle generally gives the following result: higher downforce=more fundamental, more volume, less flexible response/lower downforce= more mid-high overtones, less volume, more flexible response. Of course results, especially the amount of change, varies alot from fiddle to fiddle.

 

One example, I have been working with a fairly bright and strident fiddle, recently. Apparently, previous attempts tried to "soften things up" with a low-ish bridge, among other things, but I found raising the bridge back up to "normal" (157-159°) improved things, as it raised the amount of fundamental and low harmonics in the envelope. A bit counter-intuitive, perhaps, but it helped in this particular case.

 

An opposite case was a violin that was hard to play, and would only respond to alot of pressure, then would crack easily as soon as one went a little too far. It had a fairly normal string angle but on the steep side (154-156°). Bringing that angle "down" to 159-160° made it more enjoyable to play and easier to seek out more dynamics and timbres. I think this is a more "typical" case.

 

I'm no super adjustment guru, and I don't mean to suggest my observations are some form of "truth," but i'd be interested if others here have had different results.

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Not Telling,

This is in no way scientific, and I invite everyone to contribute if their experiences conflict with mine, but my experience with changing the string angle generally gives the following result: higher downforce=more fundamental, more volume, less flexible response/lower downforce= more mid-high overtones, less volume, more flexible response. Of course results, especially the amount of change, varies alot from fiddle to fiddle.

 

One example, I have been working with a fairly bright and strident fiddle, recently. Apparently, previous attempts tried to "soften things up" with a low-ish bridge, among other things, but I found raising the bridge back up to "normal" (157-159°) improved things, as it raised the amount of fundamental and low harmonics in the envelope. A bit counter-intuitive, perhaps, but it helped in this particular case.

 

An opposite case was a violin that was hard to play, and would only respond to alot of pressure, then would crack easily as soon as one went a little too far. It had a fairly normal string angle but on the steep side (154-156°). Bringing that angle "down" to 159-160° made it more enjoyable to play and easier to seek out more dynamics and timbres. I think this is a more "typical" case.

 

I'm no super adjustment guru, and I don't mean to suggest my observations are some form of "truth," but i'd be interested if others here have had different results.

Were those adjustments made by just bridge work only?    I thought about what Not Telling said about downforce and such.  I thought about what if I did raise the overstand without changing the neck angle.  Seems to me it could free up certain parts of the belly or back.  Then Don has his theory of what could or should happen so I kept my thoughts on hold.

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One way I like to think of string angle is in terms of bridge/top mobility. The greater the string angle, the greater the resistance to up-down motion. For example, if the string stayed straight as it crossed the bridge, there would be almost no resistance to vertical motion. If the string folded completely over the bridge at 180 degrees, resistance would be at the maximum.

 

It's probably the opposite for bridge horizontal motion though.

 

I think there's a "just right" value where a fiddle works its best, and I'm quite sure at this point that it isn't the same for every fiddle. Like so many other things about violins, one spec for string angle won't be optimal for every fiddle.

 

Curious1 has probably done more experimenting with string angle than I have, so maybe he/she :D (to preserve anonymity, not because gender is uncertain)  will comment.

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According to this tension chart, a full set averages about 50 pounds.  The strings deflect approximately 20 degrees over the bridge, creating a downforce of ~17 pounds.

 

As for messing around with the overstand, saddle height, or other things to change the downforce, I don't know what that does.  Basic physics says it should't do anything to the vibration properties, as long as the body modes are controlled by structure (bending stiffness, etc) and not static forces, which I think is the case.  I haven't tested anything, though, and lots of people think it matters.   

Great chart ; thanks Don.

This makes (some) things easily comparable.

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One way I like to think of string angle is in terms of bridge/top mobility. The greater the string angle, the greater the resistance to up-down motion. For example, if the string stayed straight as it crossed the bridge, there would be almost no resistance to vertical motion. If the string folded completely over the bridge at 180 degrees, resistance would be at the maximum.

 

It's probably the opposite for bridge horizontal motion though.

 

I think there's a "just right" value where a fiddle works its best, and I'm quite sure at this point that it isn't the same for every fiddle. Like so many other things about violins, one spec for string angle won't be optimal for every fiddle.

 

Curious1 has probably done more experimenting with string angle than I have, so maybe he/she :D (to preserve anonymity, not because gender is uncertain)  will comment.

 

That's a neat way of thinking about string angle !

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Again speaking of arches alone without incorporating the graduation leaves large portions of "it" out of the picture. If we were to do thought experiments related to building a short arch for a tunnel where we built a wood scaffold form to carry the brick load until the keystone could be inserted, we may start to ask ourselves what the different load characteristics might be based on the dimensions of our bricks, most importantly in this case, are the bricks and the structure going to be made from bricks that are the same thickness? or will we be using bricks that have been gauged and have different dimensions. Three basic designs could be 1. bricks all the same thickness. 2. Bricks that at the base of each side are thicker, and as it rises to the top, the bricks get thinner and 3. the opposite of that.

.

Most violins graduations that correspond to their arch have a #3 design, with the "roof" of the arch having the fatter dimension. This structurally, for load bearing downforce capacity is generally the weaker design of the 3, certainly able to carry a load but not the strongest. But because we are dealing with such thin dimensions the extra thickness down the middle will compensate the downforce and prevent breaking the material and shift the load bearing down the sides of the cross arch, generally right where the thickness tapers to being thinner.

 

Again it is important to always keep in mind that the strength roles of the top and back are different and that the arches serve different functions. In the back the recurve is extremely important for imparting strength that will counteract the want to "fold" the violin {long arch wise} from the wrenching action of the strings acting like a come-along, where as on the top it serves the opposite function, and adds weakness or and elastic spring/shock function once compressed with the static load.

 

The top along with the addition of the bass bar and post counteract downforce, where as the back is getting pressure added in a way that is counter load bearing. Once the static load is applied by tuning the strings to pitch the post act like a fulcrum point where the "folding" load is "balanced" on.

 

When we start to make the music by vibrating the strings we start the "earthquake" and all these pre tensioned static loads will start to respond and in essence what we have made is a wooden spring that will handle the vibration loads without catastrophic failure, yet are still very much in motion.

 

To me it is the study of the structure itself, the material and it's characteristic and how those relate to "spring theory" and the range of motion of pre loaded static loads with quantum multidirectional motion being driven into the structure that dictates "tone" and the dynamic range.

 

To me, you can focus on the notes after it has been put together, when it makes music, before that , one should focus on the structure, weakness, strength, stiffness, elasticity, where, and how much....To say the arch is important is true, but on the other hand I could draw an arch that was large and perfect, but if it's only as thick as my pencil line, it won't hold the mountain back nor the roof from caving in.

Jezzupe,  that's very enlightening reading.  Made me think, if by some chance I decide to keep making,  what species of spruce would you use?  From Europe or U.S.  I wonder if Kevin Prestwich has found the last stand of "golden age" wood in his neck of the woods?

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I'm no super adjustment guru, and I don't mean to suggest my observations are some form of "truth," but i'd be interested if others here have had different results.

 

 

I think quite the contrary : your observations are some of the most solid I am reading on MN. Combining your interest in violins / violin making with your superb playing expertise makes for the kind of insight we really need here. More posts, please !!!

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Were those adjustments made by just bridge work only?    I thought about what Not Telling said about downforce and such.  I thought about what if I did raise the overstand without changing the neck angle.  Seems to me it could free up certain parts of the belly or back.  Then Don has his theory of what could or should happen so I kept my thoughts on hold.

There's obviously a limit to what one can do just with the bridge. My observations aren't just based on those two fiddles, but some 50-60 I've set-up over the years, plus all the ones I've had done by pros while observing and discussing with them. I think alot of pros do the "different bridge height" tests to find what works best, then figure whether the result can be reached and be playable through a fingerboard replacement, a wedge, a neck pullback, a neck reset, a saddle raise or lowering, and then do the least invasive or complicated mod. I also find that "scordatura" experimenting can give me an idea whether a violin wants more or less tension and/or downforce. 

When you say raise the overstand without changing the neck angle, do you mean without changing the string angle? If you raise the overstand and keep the same neck angle, you're effectively flattening the string angle, so decreasing the downforce through the bridge, while increasing the leverage of the strings going through the feet of the bridge, effectively changing two parameters at once. I'd be wary of doing that unless I saw that a given fiddle had a tight string angle and an ultra low bridge, and showed symptoms of needing more vigorous input and less "pre-loading."

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I've put shims under the bridge (thin maple) to see whether more downforce is welcome or not.  Part of an evaluation of a slightly low neck angle.  Maybe it's lower on purpose!  Even so, if I end up fixing a low angle neck on a violin that likes it, I'll compensate with saddle or overstand to get the angle as it likes.

 

This arching discussion has me contemplating how one would make a descriptive model for the variation of arches allowing categorization.

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This is in no way scientific, and I invite everyone to contribute if their experiences conflict with mine, but my experience with changing the string angle generally gives the following result: higher downforce=more fundamental, more volume, less flexible response/lower downforce= more mid-high overtones, less volume, more flexible response. Of course results, especially the amount of change, varies alot from fiddle to fiddle.

 

My experience (limited) doesn't conflict with yours, but my reasoning does.

You can't change downforce alone without changing other things... usually you'd change bridge height.  To me, there are some huge, obvious tonal influences in doing that, which have nothing to do with downforce:

 

Higher bridge = more mass (a muting effect, most notably at the high overtones)

Higher bridge = more lever arm for lateral string motions (stronger lows and midrange, less for the E string, where bow angle creates a more vertical force)

There may also be an effect due to the mass of the strings themselves being at a larger lever arm, but I'm not sure what that might do.

 

Note that the physical reasons I mention also result in the same tonal effects you mention.  I do not see a connection between downforce and these effects.

 

 

One way I like to think of string angle is in terms of bridge/top mobility. The greater the string angle, the greater the resistance to up-down motion. For example, if the string stayed straight as it crossed the bridge, there would be almost no resistance to vertical motion. If the string folded completely over the bridge at 180 degrees, resistance would be at the maximum.

 

It's probably the opposite for bridge horizontal motion though.

 

I think there's a "just right" value where a fiddle works its best, and I'm quite sure at this point that it isn't the same for every fiddle. Like so many other things about violins, one spec for string angle won't be optimal for every fiddle.

 

If you think in more detail about "resistance to motion",  that really means a higher spring rate.  A higher spring rate, for a given mass, will show up as a higher resonant frequency.

 

I just performed a little test: low bridge, high bridge (very nearly equal masses), low tension, and high tension.  I looked at the B1+ frequency, which is about the most vertical mode of the major ones, to see how it varied.  I used viola pitch (slightly under half of standard pitch tension) for the low tension testing.  Low bridge = 29.5mm, high bridge = 34mm

 

High bridge, low tension     523 Hz

High bridge high tension    530 Hz

Low bridge low tension      528 Hz

Low bridge high tension      528 Hz

 

These are not big numbers (and there's probably +/-2Hz measurement variability).  If downforce alone was determining things, I estimate bridge height would have a 30 Hz influence, and string tension somewhere around 155 Hz. 

 

Although I can't rule out other effects that I didn't measure, or hypersensitivity of good players to small changes, I still hold the view that the other items mentioned above dominate the tonal changes, rather than the downforce.  In other words, you can't change downforce alone, and it's the "other things" that really cause noticeable change.

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Don, I didn't mean to put too much emphasis on downforce, but more on "mobility". And I understand that your tension-versus-mode frequency experiment will show some of that, and also that other factors will have an influence.

 

I'm not currently thinking so much about sound differences from moving the resonances (although moving them will certainly have an influence), but more on how this motion affects the slip-stick action of the bow. When an instrument is in good adjustment, for instance, not only does it sound better, but the bow feels very different in the way it grabs the string. The best feel and sound seem to go together, and happen within a very narrow range.

 

This also may have something to do with why different bows can sound quite different on the same violin, and why a violin can be adjusted, to some extent, to sound better than it did before with a bow which previously wasn't getting as good a sound as others. Sometimes, one can even reverse the bow preference.

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Jezzupe,  that's very enlightening reading.  Made me think, if by some chance I decide to keep making,  what species of spruce would you use?  From Europe or U.S.  I wonder if Kevin Prestwich has found the last stand of "golden age" wood in his neck of the woods?

I am very open minded related to material species, I feel any soft wood can yield pleasant tone, including, but not limited to Redwood, Fir,Cedar,Aspen as well as Spruce.

 

Currently I am working with "laked" {not ponded :D } Sitka that came from a gentlemen by the name of Daniel Hoffman, an excellent luthier and friend of Joe Robson, he has a bit of this product, but it is quite rare and has a known cut date of about 1703, if memory serves me.

 

My way and or "theory" of building, in a way, disregards specie properties and incorporates a building method that is flexible and or will work for any chunk of wood with any type of characteristic.

 

That is to simply build to what I call "stiffness and elasticity" incorporating weakness and strength.

 

A simple way of thinking about it is; if I gave you 1 piece of soft curly Maple and then one piece of say Jatoba {Brazilian Cherry} which in general is much stiffer, stronger and less elastic, both the same size say 10" x 16"... Then the challenge parameters I gave you were, 1. you will have {in this simplified case} 4 types/style/ways of bending/torqueing the material after you 2. thin both dramatically, and that 3. I am looking for a certain range of motion, say an arbitray 1/2" of "lift" or "motion" in the prescribed types of "twists" given as options for you. And or make both pieces move in a similar way related to when you torque them.

 

So the simplicity is, that once we get material down to a certain "thinness" we will obviously be able to the start to twist/tourqe/flex the material

 

{elasticity corresponds much more to the "snap back" and or once the twist load is taken off the material, how quickly will it return to it's unflexed state}

 

So if we had this arbitrary range of motion I was challenging you to achieve in both pieces, because the inherient charecteristics of each piece are so different from each other, it would be most likely a fact that you could get it to "move" in the same way, but the thicknesses would be different, same range of motion, different thicknesses required to make that happen.

 

This speaks not so much for "good" tone as it does tonal consistency. Good tone imo comes from using this "theory" along with a million other factors, but using this "scheme" to target and establish "known good ranges of motion" which will vary piece to piece, this "way" compensates for many variations.

 

Snap back and elasticity are much more dependent on the material itself, than what graduation you may do to it.

 

Hookes law and more tangent ideas related to shear forces on pretension spring loads and how thinner and thicker areas create "micro pools" that have interacting yet independent "spring actions" that are highly dependent on range of motion is much more "where it's at" than any temporary tone/mode of a free plate. Again, independent "tones" of individual parts is a very misleading way of looking at what is really going on, the only "tones" that matter with any stringed instrument are the ones that are coming out when it is being played. What dictates those tones is the structural entirety of the instrument, tones are by products of the structure, not the other way around.

 

I feel that as more people look at this from a structural challenge sort of way, incorporating structural engineering, seismic analysis , vibrational effects on structures, as may be used in auto, aeronautics, buildings, and a stronger look at Hookes law and how it dictates the entire thing, as fart as motion goes, that "good" tone will be more easily attained in a more easy and consistent way, cause, well, ya still have to build the damn thing :lol:

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Blah blah blah about my own theory...

But speaking of bizarre theories hatched by violin makers, now we've got this:

"Violin maker claims to have discovered the location of buried Nazi treasure"

The code was hidden in a piece of music!

http://www.thestrad.com/cpt-latests/violin-maker-claims-to-have-discovered-the-location-of-buried-nazi-treasure/

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HMM!  So, can I now proudly donate my sheet music of the "Accolay" Concerto to the college library?   It bears an exasperated note from my teacher:  "No!  Play softer here.  IDIOT! One more lesson like today's and you are kaput as my student."  

 

 

All these years I've been embarrassed and was just going to toss it.  But now I can claim that it doesn't cast doubt on me but is a clever code leading to the Holy Grail.  Now I wonder if the IRS will allow a greater deduction for my donation.

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For the record, the Accademia Segrito di Maestronet does not interest itself in Nazi treasures.  We leave such things for less serious scholars.  

evil-genius-smiley.gif?1292867590

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HMM!  So, can I now proudly donate my sheet music of the "Accolay" Concerto to the college library?   It bears an exasperated note from my teacher:  "No!  Play softer here.  IDIOT! One more lesson like today's and you are kaput as my student."  

 

 

...to which surely you replied with "Jawohl, mein Teacher !" and goose-stepped  out of the room.  :lol:

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Don,

What about "pre-loading?" I've long been pondering about the effect of the forces stored in the body of the violin, especially the "downward" force that could be seen as partially compressing the "springs" comprised of the back and the top/bass bar, storing a certain amount of that energy in them. As the bridge is rocking/bouncing, it is both compressing the springs further, and releasing the energy it has imparted along with that which  was "pre-loaded" into the "springs," Here, the image of "restraint" described by David Burgess would come into play in the end of the "release" cycle.

 

Your point about changing bridge mass and the lever arms of the strings is well seen, but changing the string angle does not necessarily entail any of those factors. For instance, raising or lowering the saddle, or changing the neck angle without changing the neck projection (changing the overstand in the process) can alter the "downforce" without changing any of the parameters you mentioned. I have seen quite noticeable changes in violins' behaviours in these circumstances. Some violins, especially ones thick in the wood seem to be happier with higher "pre-loading," while thinner, lighter ones seem happier with less. 

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...to which surely you replied with "Jawohl, mein Teacher !" and goose-stepped  out of the room.  :lol:

I probably would have mumbled, "I didn't think playing ooh-pah on your tuba would qualify you to be an expert on  violin dynamics," and left it at that.   :)

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I didn't mean to put too much emphasis on downforce, but more on "mobility". 

 

Since mode frequencies don't appear to change much, then bridge height would play an important part in how the string and mode interact, perhaps a squared effect:

Same string force with higher bridge = more bridge torque = stronger mode excitation

Same mode excitation with higher bridge = more bridge motion at the string

 

(all having nothing to do with downforce, except for the side effect that a higher bridge would have more downforce)

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But speaking of bizarre theories hatched by violin makers, now we've got this:

"Violin maker claims to have discovered the location of buried Nazi treasure"

The code was hidden in a piece of music!

http://www.thestrad.com/cpt-latests/violin-maker-claims-to-have-discovered-the-location-of-buried-nazi-treasure/

 

Isn't this a little early for April 1?

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But speaking of bizarre theories hatched by violin makers, now we've got this:

"Violin maker claims to have discovered the location of buried Nazi treasure"

The code was hidden in a piece of music!

http://www.thestrad.com/cpt-latests/violin-maker-claims-to-have-discovered-the-location-of-buried-nazi-treasure/

I don't know, Dave.  Looks like to me an instructor of sorts was telling a lessor Euphonium or trombone player where to take his breaths.  Could be for bassoon.  If it's a map one would have to be on his game and half crazy to figure that out.  A high powered metal detector wouldn't hurt, either.  

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