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Two Wolves (Romulus and Remus?)


Shunyata
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My latest build has been regularly played for about 4 weeks.  It has two wolves, one between near G (on the G string, one octave up from open string) and the other at B nat just above.  That whole range doesn't speak very well.

Both wolves seem to have developed over time.  

No wolves on the other strings.  In general the Gs  and B-Cs throughout the violin have extremely rich color - I am guessing related to the wolves.

Any suggestions for construction or setup for managing the wolves... although the rest of the violin sounds so nice I am tempted just to learn to live with it.

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Apparently you have wolves at both the B1- and B1+ resonances, and at approx. 400 and 500 Hz respectively, the frequencies are abnormally low... suggesting either poor wood or graduations that are too thin, or a bass bar that is too flexy.

There are too many variables in the arching, wood, and graduations that enter into wolfiness, and without knowing exactly what you have, it's not easy to make more detalied suggestions... at least for me.

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Do you think a slightly long neck might contribute to the issue?

I followed the Johnson and Courtnall bass bar dimensions.

The graduations were thinner than I usually do... 2.1mm to 2.2mm in the lungs, in an effort to get the weight down to a reasonable level.

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38 minutes ago, Shunyata said:

Do you think a slightly long neck might contribute to the issue?

I followed the Johnson and Courtnall bass bar dimensions.

The graduations were thinner than I usually do... 2.1mm to 2.2mm in the lungs, in an effort to get the weight down to a reasonable level.

That is pretty thin and just might be the culprit, start globbing on some blue tack in the thin areas and see if you can't tame them, if you can by adding weight, you can always pop the top and add some material patches to increase the heft and thickness.

Lung hollowing must be done carefully, to think of it as two areas off the side of the spine can get you in trouble, the "two drumskins" on the left and right can really cause problems , often times a third hollow , or drastically asymmetric shape and depths  {1 to .5} need to be employed } lest too close of symmetry can start competing with each other and cause interference. 

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1 hour ago, Marty Kasprzyk said:

I suggest adding a second sound post located below the bass side lower f hole eye to limit top plate motion in that area.

Hmm, ya I have one instrument I did that to, a very thin flat top balsa, and it did work, so that's an idea.

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4 hours ago, Shunyata said:

I will try.  Thank you.

also don't let weight targets steer the ship, look for adequate range of motion with an asymmetrical carve favoring slightly more motion on the treble side , while always using mechanical sympathy to do so.   

there is nothing wrong with having an idea in your head what a weight should be, but I would not shoot for precise weights....and if you absolutely have to shave weight I suggest spreading it out around the entire plate rather than "drum skinning" regions, even though there are definitely areas we want thicker and thinner.

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On 9/12/2021 at 10:11 AM, Shunyata said:

My latest build has been regularly played for about 4 weeks.  It has two wolves, one between near G (on the G string, one octave up from open string) and the other at B nat just above.  That whole range doesn't speak very well.

Both wolves seem to have developed over time.  

No wolves on the other strings.  In general the Gs  and B-Cs throughout the violin have extremely rich color - I am guessing related to the wolves.

Any suggestions for construction or setup for managing the wolves... although the rest of the violin sounds so nice I am tempted just to learn to live with it.

I would review the string angle first, a higher saddle can diminish the effect by increasing the string angle (making it flatter)
 

Then the stiffness of the tailgut between tailpiece and saddle can worsen things. Could it be that you are using a plastic tailgut and it stretched out? In any case I would keep it there as short as possible.

All this does not kill the wolves but can tame them. 

 

Edited by Andreas Preuss
Correction and clarification
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50 minutes ago, Andreas Preuss said:

Then the stiffness of the tailgut between tailpiece and saddle can worsen things. Could it be that you are using a plastic tailgut and it stretched out? In any case I would keep it there as short as possible.

But isn't this a contradiction? If you shorten the tailgut (bringing the tailpiece closer to the saddle) the tailpiece / tailgut system stiffens.

Am I missing something?

If the goal is to make it more elastic, maybe you could try to cross the tailgut, but I think it can only be done with kevlar/carbon ones.

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I am using plastic tailgut... and a Wittner style tailpiece, which I don't usually use.  The tail piece seemed kind of long to me, with almost no exposed tailgut past the saddle to get 54mm string afterlength.  Maybe a shorter tailpiece would be in order?

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4 hours ago, Davide Sora said:

But isn't this a contradiction? If you shorten the tailgut (bringing the tailpiece closer to the saddle) the tailpiece / tailgut system stiffens.

Am I missing something?

If the goal is to make it more elastic, maybe you could try to cross the tailgut, but I think it can only be done with kevlar/carbon ones.

No, the goal is not to make it more elastic at the tailgut. For wolf notes I want to control the pivoting movement of the bridge as much as possible. Sometimes I wonder if a wider than usual spacing of the tailgut on the saddle wouldn’t help. 

Or, in your experience, does it help to make it looser there?

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42 minutes ago, Andreas Preuss said:

No, the goal is not to make it more elastic at the tailgut. For wolf notes I want to control the pivoting movement of the bridge as much as possible. Sometimes I wonder if a wider than usual spacing of the tailgut on the saddle wouldn’t help. 

Or, in your experience, does it help to make it looser there?

No, I'm on your line, stiffer would be better. Except in cases where the opposite is better:), but in my limited experience they have never happened. I mentioned the crossed tailgut, because I sometimes see it, but I don't like it and I don't think it works well. Have you ever tried? I don't.

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1 hour ago, Davide Sora said:

No, I'm on your line, stiffer would be better. Except in cases where the opposite is better:), but in my limited experience they have never happened. I mentioned the crossed tailgut, because I sometimes see it, but I don't like it and I don't think it works well. Have you ever tried? I don't.

I am experimenting with a single tailgut tailpiece on my new concept violin. The idea is if the pivoting motion is blocked nowhere more energy is used on the body for this motion. (Certainly a completely unscientific statement) 

This means in return that the body of the violin must have resistance in cross grain direction, which is on well built instruments basically never the case.  So if you want to make an instrument built like brick somehow function ‘better’ the single tailgut or a crossed tailgut is an option. 
 

I came now back to the single tailgut tailpiece on my new concept violin for two good reasons: it drives better a bridge with very wide feet (46mm) and a top with an x bass bar (which ‘artificially’ stiffens the top in cross grain direction.) 

 

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1 hour ago, Andreas Preuss said:

I am experimenting with a single tailgut tailpiece on my new concept violin. The idea is if the pivoting motion is blocked nowhere more energy is used on the body for this motion. (Certainly a completely unscientific statement) 

This means in return that the body of the violin must have resistance in cross grain direction, which is on well built instruments basically never the case.  So if you want to make an instrument built like brick somehow function ‘better’ the single tailgut or a crossed tailgut is an option. 
 

I came now back to the single tailgut tailpiece on my new concept violin for two good reasons: it drives better a bridge with very wide feet (46mm) and a top with an x bass bar (which ‘artificially’ stiffens the top in cross grain direction.) 

 

This makes sense, thanks for sharing your experience.

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Almost all of the rigid-body tailpiece modes are below the playing range, and far below the frequency of wolf notes.  Simple translation: it won't do diddly to a wolf.

The one exception is the end of the tailpiece as sprung by the tailgut.  I generally keep the free gut length as short as possible, which keeps this resonance high and damped, so it's not noticeable. If the free gut gets much longer than ~5mm (for nylon type; single gut and kevlar cord would be flexier), the resonance gets down around the wolf range to where things can happen.  Only if the resonace is tuned exactly to the wolf, it can be tamed.  Slightly off, and it gets worse.  I have tried this a few times, and it works... but the effort to keep it tuned, and the odd transients that come with it made it not worth it.

Another exception:  extremely light boxwood tailpieces can have another rigid-body mode that creeps up into the playing range, which is not good... but still nowhere near wolf frequencies.

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2 hours ago, Andreas Preuss said:

I am experimenting with a single tailgut tailpiece on my new concept violin. The idea is if the pivoting motion is blocked nowhere more energy is used on the body for this motion. (Certainly a completely unscientific statement) 

This means in return that the body of the violin must have resistance in cross grain direction, which is on well built instruments basically never the case.  So if you want to make an instrument built like brick somehow function ‘better’ the single tailgut or a crossed tailgut is an option. 
 

I came now back to the single tailgut tailpiece on my new concept violin for two good reasons: it drives better a bridge with very wide feet (46mm) and a top with an x bass bar (which ‘artificially’ stiffens the top in cross grain direction.) 

 

I'm curious, how are you doing the loop around the endpin so you get equal pull, I assume when it comes to tail you have a single drill hole centered with the gut going in and knotted off? Simple as it sounds I'm having a hard time "engineering" a single gut in my mind.

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Shunyata, have you tried blu tack globs on the thin spots yet? If you have, and it works, make sure you mark the location and save the glob in order to weigh it so if you can make an underpatch the same if you are going to go that route. Obviously, start with small globs and work your way up.

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Before taking any action I am "taking notes" to better understand what is happening with the instrument.

The last few days the G/G# wolf has virtually disappeared - although that range isnt the sweetest on the violin.

At the same time the B wolf has intensified, to a wobbly but useable note.

Humidity is lower lately.

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