Eliminate Wolf tone during construction


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Hello everyone regarding wolf tones is it possible during the construction of the instrument to be able to avoid the wolf? What are the things to avoid. For example is carving to thin a top plate a cause?  They appear more common in the cellos and double basses as well as violas could this be due to the larger surface areas of the plates. I ask because having completed violin number 7 which is  Guarneri pattern which I made slightly larger in the lower bout I now have a wolf on the D string at G the top plate in the lower bout area is 2mm thick. The previous violins I never had a wolf so am suspicious about the larger and thinner top plate on number 7. I removed the top and reduced the height of the bass bar to see what effect it might have, but wolf still there. Any other suggestions to experiment with? A larger bass bar, putting a patch or cleat near the end of the bass bar between the bass ff hole? I am actually glad to have the wolf as it gives me a challenge to try and tame it. So any suggestions are welcome and I can report back with the results. Thank you in advance 

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Hello, did you checked tap tone of the full body , and tap tone of the neck (with strings damped), do you see your wolf note somehow in the spectrum?

Could be interesting that you share the spectrums and also your wolf note frequence.

I noticed on a previous instrument an influence of the neck main mode.

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It is somewhat unusual to have a wolf on the B1- mode; usually it is the B1+, at C to C# on the A string.  I would tend to look into the back plate rather than the top... but it could be arching, graduations, relative plate weights, bass bar... so it's hard to say much.

One thing I would try would be to move the soundpost away from the centerline, particularly the end that hits the back plate.  This might require a tilt in the post.

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There are many factors in what causes wolf notes but my approach to any problem is to look at what you know is out of normal specs. I would say that a top thickness of 2 mm is unusually thin and unless the wood is extremely stiff that is likely to be your problem. Also inconsistency in graduation is likely to cause wolf tones in strange places. Even a 0.1 mm variation in a 2 mm thick plate will be a serious problem especially in the area just below the FF.

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On 12/31/2020 at 3:37 PM, GerardM said:

Hello everyone regarding wolf tones is it possible during the construction of the instrument to be able to avoid the wolf? What are the things to avoid. For example is carving to thin a top plate a cause?  They appear more common in the cellos and double basses as well as violas could this be due to the larger surface areas of the plates. I ask because having completed violin number 7 which is  Guarneri pattern which I made slightly larger in the lower bout I now have a wolf on the D string at G the top plate in the lower bout area is 2mm thick. The previous violins I never had a wolf so am suspicious about the larger and thinner top plate on number 7. I removed the top and reduced the height of the bass bar to see what effect it might have, but wolf still there. Any other suggestions to experiment with? A larger bass bar, putting a patch or cleat near the end of the bass bar between the bass ff hole? I am actually glad to have the wolf as it gives me a challenge to try and tame it. So any suggestions are welcome and I can report back with the results. Thank you in advance 

Are you self-taught, or went to violin makers school?

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8 minutes ago, nathan slobodkin said:

 Even a 0.1 mm variation in a 2 mm thick plate will be a serious problem especially in the area just below the FF.

Below the bass F hole is definitely sensitive for the "normal" wolf around C.  A wolf on G is a different mode shape, and I'm not sure a G wolf is sensitive in that spot (I haven't run across any strong G wolfs, so I'm mostly making a theoretical guess).

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On 1/3/2021 at 12:42 AM, Wood Butcher said:

Are you self-taught, or went to violin makers school?

I’m self-taught. Having said that I was an apprentice cabinet maker at 15 years old been in the trade all my life. Am now retired and taken up violin making.

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On 12/31/2020 at 10:37 AM, GerardM said:

Hello everyone regarding wolf tones is it possible during the construction of the instrument to be able to avoid the wolf? What are the things to avoid. For example is carving to thin a top plate a cause?  They appear more common in the cellos and double basses as well as violas could this be due to the larger surface areas of the plates. I ask because having completed violin number 7 which is  Guarneri pattern which I made slightly larger in the lower bout I now have a wolf on the D string at G the top plate in the lower bout area is 2mm thick. The previous violins I never had a wolf so am suspicious about the larger and thinner top plate on number 7. I removed the top and reduced the height of the bass bar to see what effect it might have, but wolf still there. Any other suggestions to experiment with? A larger bass bar, putting a patch or cleat near the end of the bass bar between the bass ff hole? I am actually glad to have the wolf as it gives me a challenge to try and tame it. So any suggestions are welcome and I can report back with the results. Thank you in advance 

Lighter tension strings might help.

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7 hours ago, GerardM said:

I’m self-taught. Having said that I was an apprentice cabinet maker at 15 years old been in the trade all my life. Am now retired and taken up violin making.

Thank you. I wondered what access to instrument making information you’d had.

When you say you made a wider lower bout, how wide is it now?

I can’t offer any help on how to resolve this issue, I’ve never run across a wolf there. In my experience, they have been pretty much in the B-C range exclusively on violins.

Could it not be a sympathetic resonance from the open G? Does it stop if you damp all of the other strings, or when damping the strings behind the bridge?

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8 hours ago, GerardM said:

I’m self-taught. Having said that I was an apprentice cabinet maker at 15 years old been in the trade all my life. Am now retired and taken up violin making.

Welcome! You’re in the right place. William Conant also followed that path. You’re not in Vermont are you?

 

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Posted (edited)
16 hours ago, Wood Butcher said:

Thank you. I wondered what access to instrument making information you’d had.

When you say you made a wider lower bout, how wide is it now?

I can’t offer any help on how to resolve this issue, I’ve never run across a wolf there. In my experience, they have been pretty much in the B-C range exclusively on violins.

Could it not be a sympathetic resonance from the open G? Does it stop if you damp all of the other strings, or when damping the strings behind the bridge?

I made the lower bout 6mm wider and the rib height I increased by 1 mm at the tail end, giving 32 height at the tail and 30mm at the neck. My theory being it might be a little more viola sounding without having the larger instrument. It’s definitely not resonance from the open G string. Moving the finger slightly up or down from the note and the wolf note disappears. I have just tuned the instrument down half a tone and the wolf note has gone. Also with the strings tuned up to pitch I fitted one of those brass wolf tone eliminator devices to the G string and it reduced the wolf considerably. I found when playing if I moved the bowing position slightly up or down then there was no wolf note. 

Edited by GerardM
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23 hours ago, GerardM said:

I made the lower bout 6mm wider and the rib height I increased by 1 mm at the tail end, giving 32 height at the tail and 30mm at the neck. My theory being it might be a little more viola sounding without having the larger instrument. It’s definitely not resonance from the open G string. Moving the finger slightly up or down from the note and the wolf note disappears. I have just tuned the instrument down half a tone and the wolf note has gone. Also with the strings tuned up to pitch I fitted one of those brass wolf tone eliminator devices to the G string and it reduced the wolf considerably. I found when playing if I moved the bowing position slightly up or down then there was no wolf note. 

From what you describe, it does sound like it is a wolf.
However, I do not know if the changes to the body size are enough, to change the main body resonance to G from where it would usually be around B-C.
Even on a viola, the Wolf, if present is likely to be around F#, so you have somehow got very close to this.

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1 hour ago, Wood Butcher said:

From what you describe, it does sound like it is a wolf.
However, I do not know if the changes to the body size are enough, to change the main body resonance to G from where it would usually be around B-C.
Even on a viola, the Wolf, if present is likely to be around F#, so you have somehow got very close to this.

I have also tried another method. Having tuned up to pitch I attached two small coins to the tail piece ( I have not weighed the coins) using blue tac if I placed them on the G D string side it cured the wolf, if placed in the centre there was a slight wolf. I have found this experience very educational. Regarding the weight of the tail piece, would you attach a small piece of lead ( are there weights available for this purpose) to the underside of the tail or search for a heavier tail piece? Thank you again for all your help and everyone else for their contributions.

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On 1/5/2021 at 2:08 AM, GerardM said:

I made the lower bout 6mm wider...

3 hours ago, Wood Butcher said:

I do not know if the changes to the body size are enough, to change the main body resonance to G from where it would usually be around B-C.

On a 16" viola I built, the B1+ resonance (usual wolf on a violin) only got down to A, so I don't think you could get it down to G on a violin and still have it work at all.

The extra 6mm on the lower bout seems like a likely suspect.  Also on my violas, the lower resonance (B1-) often is the strongest, and that has never happened on any of the violins so far.  This would indicate that increasing body size tends to move strength to the lower resonance.

 

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Thanks Don just been reading your articles on “What you can Find out by Hitting Things”  plus “Violin Acoustics Overview”  and “Sound Analysis” I did wonder how you  found these B1- and B1+ frequencies amongst others. I was just tapping the Mode 5 and setting back and front a half or full tone apart. I guess I got lucky as family members who play professionally remarked how well the violins sounded. So is it vital to use audacity software? I have an audio tool on my mobile which tells me the Hz so I know what the musical note is. However does audacity give a more in-depth view of things? One things for sure I find it easier making an antique inlaid piece of furniture compared to fathoming violin acoustics.

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^Audacity used the right way can give you a graph of the intrinsic relative loudness of all the notes in your fiddle (and the notes between the notes).  Many products have the same capability, but Audacity is the only free one (that I know of).  Certainly the most popular

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11 hours ago, GerardM said:

 I did wonder how you  found these B1- and B1+ frequencies amongst others.

It's usually pretty easy, and the frequency range where they can be found is very limited.  Sometimes they are split and not so obvious, but that's less often.

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Here is B1- and it's relationship to the soundpost.1776623486_bodymodes10.JPG.3947902e51b8bb584cd84932578a3179.JPG1358603384_bodymodes4.JPG.e762119780a6aea96de37b88ec14eaf5.JPG

You can see that the area below the bridge is active on B1- , too thin in this area, esp. with extra wide bouts could cause some problems.

As far as building to reduce the risk of a wolf in this area,, which is usually on B1+,

Peter KG  http://www.thestradsound.com     

offers this solution, a tenth or two thicker when building, thin down only as necessary.

935980841_wolfnoterepair.thumb.JPG.4b83b9a189ba0117f52dfc503660ea30.JPG

174233283_bodymodes2.JPG.40fccedb947ace41adcbc012c2363901.JPG

G at 392 is a bit low for B1-. Maybe your B1- is low. You could tap around on the back, probably the lower bout using audacity and see what you can find, or below the bass f-hole. You will find it somewhere.

place a wedge under the fingerboard in different places and check. also a wedge under the tailpiece in various spots to see if it changes anything.

1904807937_bodymodes1.JPG.7a8a26c2c3e31ecb3a268657dfc48e11.JPG

 

        B1+   Just  Because.

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16 hours ago, Bill Merkel said:

^Audacity used the right way can give you a graph of the intrinsic relative loudness of all the notes in your fiddle (and the notes between the notes).  Many products have the same capability, but Audacity is the only free one (that I know of).  Certainly the most popular

Here's and example of scale note loudness taken from Audacity tests and replotted in Excel.

The loudness of the f and f# notes are higher than the others and this is where wolf notes are  a problem.

Screen Shot 2021-01-07 at 11.01.02 AM.png

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7 hours ago, GerardM said:

Thank you Evan for the information there’s a lot to think about. I will try the wedge suggestion and report back. 

Also notice that a longer soundpost toward the center increases the HZ of the B1-  rapidly.

another place to diddle around,,,,,,,,,,,

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