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How does a violin reproduce overtones? - Theorizing a model


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8 hours ago, Marty Kasprzyk said:

There's no sense in beating a dead horse.

No, but examination of dead horses gives doctors insight into the anatomy. For this the entire work of your experiments is very interesting. Besides do you have a sound clip somewhere available?

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9 hours ago, Don Noon said:

unless you happen to be using non-linear springs.

Is wood a linear spring? 
 

Could it be that tension applied changes the relation of longitudinal stiffness to cross grain stiffness? In the end wood is a ‘complicated’ material.
 

Just guessing. 

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14 hours ago, Marty Kasprzyk said:

These reductions of loads on the top plate allows the use of a thin flat plate made from low density (0.28g/cc) Pawlonia wood which reduces the plate's weight.  The elimination of the arching reduces the plate's stiffness and the combination of these two effects increases the plate's admittance which increases the instrument's sound output.

The reduction of plate stiffness also increases the modal density which means there are more resonance peaks in the frequency response curve which in turn makes the various notes in a scale more even in loudness.


Marty, thanks for your detailed explanation. 

I think this is all very interesting for engineering a violin. (To me more interesting than theories which in the end don’t say how to do what)

i was trying to translate this in my head to my new concept violin and I think there are parallels.

1. I think I reduced the buckling compressive forces by massively strengthening the linings only on the top side. I tripled the thickness to 6mm combined with a normal height of 8mm. The only weak point is still the region around the top block and therefore it might in the end be a good idea to stabilize this area more from the ribs.

2. With this construction installed, I could see (or rather hear) repeatedly that the ‘normal’ downforce from the bridge is too much. This resulted in my decision to augment the overstand of the neck to 10mm lowering the string angle to 161-2 degrees (And maybe that’s still not enough) My top has a rather low arch around 14mm right now.

However, from your comments I often get some sort of reconfirmation that I am walking in the right direction.
 

Reanimation of a dead horse by heart transplant?

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17 hours ago, Don Noon said:

The back doesn't move, but the top does.

I guess this is short term measurements, just after the stringing and some time after. Backs do distort over time, maybe mainly in humid periods. Tops do creep too and they move due to humidity variations. I am sure you have seen the measurements om the Cannon. Very small changes. Violins in normal non humidified conditions may see larger variation. Maybe mot comes above 50-60% but still.
I wish we cold have some laser moire setup to see the changes at tension and humidity varation. A German researcher used some kind of "mosquito net" and lights to get iso-arch heights and photographed it. Maybe the method is sensitive enough for seeing small changes in arch shape from tension and humidity variations?

Hermann Neugebauer und Gerhard Windischauer "3D-Fotos Alter Meistergeigen" Wölbunghöhen, etc, Verlag Erwin Bochinsky, Frankfurt, 1998

Edited by Anders Buen
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7 hours ago, Andreas Preuss said:

Is wood a linear spring? 

Could it be that tension applied changes the relation of longitudinal stiffness to cross grain stiffness? 

Yes, for the small deflections of a violin.

No.

1 hour ago, Anders Buen said:

Backs do distort over time, maybe mainly in humid periods.

Yes.  My comment was about shorter term loading, not long-term creep.

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19 hours ago, David Beard said:

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?

That assumes the heft or strength of the spring is equal?  In this case the back spring 99% of the time will be stronger than the top spring. 

When Don says the back does not move, I am assuming that is when the post is first inserted, meaning it acts like a floor, when the post is being wedged in it is the top that rises....correct Don?

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21 minutes ago, jezzupe said:

I am assuming that is when the post is first inserted, meaning it acts like a floor, when the post is being wedged in it is the top that rises....correct Don?

No, the soundpost is being compressed.

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The soundpost does not compress, as it is longitudinal grain and very stiff.

The back is also very stiff.

The top is not very stiff (re: treble side).

So inserting the soundpost raises the top (mostly), depending on pressure.  Tensioning the strings doesn't move things on the treble side much, as it is supported by the stiff back and very stiff soundpost.  Top stiffness adds a little bit, but it is mostly the back providing support.

These are generalizations, as in reality nothing is infinitely stiff.

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On 5/24/2021 at 11:23 AM, Andreas Preuss said:

How does a violin reproduce overtones?

Most everything on earth reproduces from some form of "the horizontal bop", whether truly horizontal, hanging from a tree upside down, or inclined at other angles.

Do you keep motion-sensing and recording cameras on your fiddles overnight, or whenever you are not there, to observe the shenanigans?

Gawd, I hope the "orbs" recorded on the camera in my wood storage room are the ghosts of Stradivari.  So far, so good.

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On 7/23/2021 at 6:04 PM, jezzupe said:

 

Most all violin, or violin like objects will produce and then reproduce overtones, we must choose how much, in what way and then really "why and how" also , and then ask how much time we want to put into finding that out vs being in the shop building 

A bowed violin string produces all of the overtones of a note in a saw tooth wave form. But because it is so narrow it can't move much air when it vibrates so it produces very little sound.  Therefore the string is connected via a bridge to a much larger surface area violin body which can efficiently radiate sound.

The bridge and the violin shell have many resonances which can increase or decrease the relative strengths of the string's harmonics produced thus they act as filters of the harmonics. They don't produce the harmonics.

A

ttached below is one of Colin Gough's diagrams of this sequence.

711182422_ScreenShot2021-05-24at9_02_55PM.thumb.png.751aec9be1e5f78c84705c4f05e11f97.png

 

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21 hours ago, Andreas Preuss said:

No, but examination of dead horses gives doctors insight into the anatomy. For this the entire work of your experiments is very interesting. Besides do you have a sound clip somewhere available?

These are undergraduate students using three of my instruments at the Crane School of Music in Postdam NY  while playing Ellen Schwindt's 2019 composition "Trio for three friends".  Matt Grosso is on the right side playing a violin part on 5 string viola.

Ellen Schwindt has made some interesting comparisons with music's progressions of harmonic overtone series and Mandlepbrot's fractals where smaller and smaller pieces retain the same form.  Sort of like me making sawdust out of large pieces of wood.

 

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5 hours ago, Marty Kasprzyk said:

A bowed violin string produces all of the overtones of a note in a saw tooth wave form. But because it is so narrow it can't move much air when it vibrates so it produces very little sound.  Therefore the string is connected via a bridge to a much larger surface area violin body which can efficiently radiate sound.

The bridge and the violin shell have many resonances which can increase or decrease the relative strengths of the string's harmonics produced thus they act as filters of the harmonics. They don't produce the harmonics.

A

ttached below is one of Colin Gough's diagrams of this sequence.

711182422_ScreenShot2021-05-24at9_02_55PM.thumb.png.751aec9be1e5f78c84705c4f05e11f97.png

 

When I said "most" I really did mean all, but were including things like electric baseball bat violins that you really can't hear unless they are amplified, so,but ya what you said he said.

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10 hours ago, David Burgess said:

Most everything on earth reproduces from some form of "the horizontal bop", whether truly horizontal, hanging from a tree upside down, or inclined at other angles.

Do you keep motion-sensing and recording cameras on your fiddles overnight, or whenever you are not there, to observe the shenanigans?

Gawd, I hope the "orbs" recorded on the camera in my wood storage room are the ghosts of Stradivari.  So far, so good.

"ya, I tried to convince him that the orbs were artifacts of digital cameras and dust, but well , he still thinks his attic is haunted and that all the violins are Strad's , so were working on a long term care situation for him now" :lol:

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2 hours ago, Marty Kasprzyk said:

These are undergraduate students using three of my instruments at the Crane School of Music in Postdam NY  while playing Ellen Schwindt's 2019 composition "Trio for three friends".  Matt Grosso is on the right side playing a violin part on 5 string viola.

Ellen Schwindt has made some interesting comparisons with music's progressions of harmonic overtone series and Mandlepbrot's fractals where smaller and smaller pieces retain the same form.  Sort of like me making sawdust out of large pieces of wood.

 

I think they really pretty good and interesting, they have their own unique voices and well if someone just played the audio I would not have said, ah well these clearly are violins that are built completely differently, there are some places that are  different sounding in the lower registers, but actually for the more contemporary stuff I think the tonal structure is apropos. They do not have Strad power and tone, but people need to understand, that , that tone is not always appropriate for the many styles of music that now exist, and as much as one can love "the classics, with that Strad sound" one can not deny the reality that moving forward is happening in many different ways, many which "we" may not appreciate musically, but it's happening one way or another if we like it or not.

 

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6 hours ago, Marty Kasprzyk said:

These are undergraduate students using three of my instruments at the Crane School of Music in Postdam NY  while playing Ellen Schwindt's 2019 composition "Trio for three friends".  Matt Grosso is on the right side playing a violin part on 5 string viola.

If I may ( respectfully ) ask : what's the point of that ?

Are they supposed to be an improvement over "normal" instruments ????   Because they sound NOTHING like those. 

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8 hours ago, jezzupe said:

1. They do not have Strad power and tone, but people need to understand, that , that tone is not always appropriate for the many styles of music that now exist,

2. and as much as one can love "the classics, with that Strad sound" one can not deny the reality that moving forward is happening in many different ways, many which "we" may not appreciate musically, but it's happening one way or another if we like it or not.

1. ... and nobody listens to. :)

2. Once you stop moving backwards the illusion of other things moving forwards disappears.   :)

 

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9 hours ago, Marty Kasprzyk said:

These are undergraduate students using three of my instruments at the Crane School of Music in Postdam NY  while

I think the viola is best for sound. All instruments seem to have a violaish timbre. This means that they have a warm and not too aggressive sound. But this might be as it is because I heard a world class player on a violin which sounded like a viola and can only guess why he/she chose to play such an instrument. 
Without playing your instruments myself there is not much more I could say about it.  I can only guess that probably the biggest ‘problem’ for professional players is the flexibility of the sound and from what I hear I would also guess if a violinist gets really heavy with the bow the violin will not function any more.

If I would imagine any music for your instruments it would be some sort of meditative music. (Arvo Pärt?)

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2 hours ago, Carl Stross said:

If I may ( respectfully ) ask : what's the point of that ?

Are they supposed to be an improvement over "normal" instruments ????   Because they sound NOTHING like those. 

That's the point.

These players liked playing something different from the normal.  Other players and listeners don't.

 

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1 hour ago, Marty Kasprzyk said:

These players liked playing something different from the normal.  Other players and listeners don't.

There is definitely an abnormal sound to these instruments.  You could say that they sound like their maker.

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4 hours ago, Carl Stross said:

..... i really don't know what else to say.

Andreas did ask for a sample and that is what was offered.  For a Sunday morning - pleasant sounding enough for me.

The violin on the left is comparable to some Amati's I've heard before.  The player in the middle may not be quite up to snuff technique wise {just my guess} and I just can't make a decision with the instrument on the right other than maybe a little bit more vibration production could help.

Do they compose music like that in your native Greenland/Iceland?

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3 hours ago, Marty Kasprzyk said:

That's the point.

These players liked playing something different from the normal.  Other players and listeners don't.

 

I see. 

Well, thank you very much for giving us the opportunity to have a listen -I always wondered how that "anti-violin/viola" of yours sounds.

You probably don't know this but there was in the '60s a Hungarian (?) maker who tried to duplicate all the strings with appropriately tweaked violin like objects. I heard small chamber assembles playing his instruments and it wasn't intolerable. Not an experience one would wish to repeat either...

 

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