Update on Wolf tone at C (B1+)

[Peter K-G]

Eliminating the wolf at C

http://www.thestradsound.com/research/wolf-note

[uncle duke]

Is it possible the bassbar is not properly shaped?  What about the belly arching being to high still?  Does it matter if the block gluing area goes all the way across laterally?   What causes wolf notes?

[Peter K-G]

In my case it is overstrong B1+ at 525-530 Hz (with chin rest). Four last violins are tuned to the same frequency with backs weighing 97-100 g. Their tops are all different weighing 65-70 g, with different graduation and bass bars shapes. All four violins are also varnished differently. From thickish and hard to soft and very thin. It is the weight of the back plate and the bass bar that causes this effect. There are many options to do differntly for me but I'm going to make 10 copies as close as possible. I need to tame the wolf because I'm not going to change the other parameters for this set.

The tops arches varies are 15,5 - 17 mm and the back arches 15 - 16 mm

[Doug Cotterill]

Which C, Peter? On the A string? D string? High up on the G string? All of them?

[Peter K-G]

Which C, Peter? On the A string? D string? High up on the G string? All of them?

Yes all of them, worse on D and really bad on G string up high. Even Lower C on G string wolfs

[tango]

I have  a very little cut of the vibrations of the in C note in IV string, like a weak wolf.

Really is weak but is there. I must search how to eliminate (strings  tail gut, distance tail-bridge? who knows).

[Peter K-G]

For what it's worth I have found the solution for C wolf elimination on soloist violins with B1+ tuned to 520-530 Hz.

This is within the limit that the plates are graduated as typical Stradivari violins, with light plates

(top 65-70 g/95-100 g) and adjusted to the woods density. (+/- 0,2 mm). 

 

Some background is found here when I started the research on how to control the modes dB beside controlling their pitch. 

Body modes as violin sound equaizer

http://www.maestronet.com/forum/index.php?/topic/327789-body-modes-as-violin-sound-equalizer/

 

Accidentally I got an important piece in the puzzle when re tuning an old German factory violin:

 

This one got a "split" and the C wolf occurred at its harmonics A and D. 

 

Without any sacrifice to the sound:

• Increase thickness in the area below the bass f-hole and towards the middle
• move the bass bars highest point backwards behind the bridge.
• Tune the bass bar to what you normally would do (light and stiffness to the initial M5 frequency)

 

This assuming that you want such a soloist violin sound as described above. Not everyone prefer such violins as they are quite powerful and sensitive.

 

 

  

[Peter K-G]

It's this peak you want to tame (lower image):

 

[uncle duke]

Without any sacrifice to the sound:

• Increase thickness in the area below the bass f-hole and towards the middle
• move the bass bars highest point backwards behind the bridge.
• Tune the bass bar to what you normally would do (light and stiffness to the initial M5 frequency)

 

Couldn't a cleat or small eyebrow work instead of inlaying a big patch?

 

I just saw the new graph.  So you are saying just by adding wood that the red area will open up/send a signal enabling vibration to turn into the blue area?

[Peter K-G]

A small cleat (0,5 g) Will work if you hit the right spot.

When you make a new violin make the area thicker 0,2 mm

[Don Noon]

It's this peak you want to tame (lower image):

 

B1+Down.JPG

B1+Up.JPG

 

Where did these come from?

Why are they different from the B1+ mode shape I'm familiar with, and why are there so many antinodes?

Why are the "up" and "down" maps different?  Shouldn't they just be opposite signs?

[Peter K-G]

Where did these come from?

Why are they different from the B1+ mode shape I'm familiar with, and why are there so many antinodes?

Why are the "up" and "down" maps different?  Shouldn't they just be opposite signs?

 

One of the key is to understand B1 modes. I have spent thousands of hours thinking about this before I solved how they work (in my head). The main problem is that the 3D images are so exaggerated that one misses the speed and motion combination (imaginary thinking).

 

You have the DVD - 

• B1+ “Breathing” modes

[Peter K-G]

 

One of the key is to understand B1 modes. I have spent thousands of hours thinking about this before I solved how they work (in my head). The main problem is that the 3D images are so exaggerated that one misses the speed and motion combination (imaginary thinking).

 

You have the DVD - 

• B1+ “Breathing” modes

 

 

It is public also:

http://strad3d.org/demo/st_10.html

[Don Noon]

It is public also:

http://strad3d.org/demo/st_10.html

 

Those look like some Stoppani animations, although it's not abundantly clear what it's an animation of, and why there are 3 different ones, each with some different kind of stiffness direction, and they all appear to be of a flat plate.  I don't think it is the B1+ of any real instrument.

[Peter K-G]

These animations can be in my opinion very misleading. In any case B1+ peaks near lower bass f-hole and towards the middle. This is also shown from experiments on real violins (Stoppani/Kreit)

 

 

SMAC 2013 Stoppani

2013_Acoustic_measurements_in_the_workshop.pdf

 

If you have a violin that Wolfs on C as described, a spot can be found when playing, preferable G string up high where it is horrible. Have someone near gently search for the spot with his finger and put a small weight there and the wolf is eliminated.

 

There is an opposite spot lower on the back plate, but that one needs a ~5 g weight and changes the sound (somewhat "squeezed") 

 

 

[David Burgess]

 

 

If you have a violin that Wolfs on C as described, a spot can be found when playing, preferable G string up high where it is horrible. Have someone near gently search for the spot with his finger and put a small weight there and the wolf is eliminated.

 

There is an opposite spot lower on the back plate, but that one needs a ~5 g weight and changes the sound (somewhat "squeezed") 

Based on my own experience, I'd say that it would be more accurate to say the wolf has been moved to a different note.

I'll add that I haven't run across any wolf elimination strategy, which doesn't change the overall character of the sound, and the impression of the change in sound is often negative.

[Addie]

That's because, if you change how the plate moves at one frequency, you probably change how it moves at other frequencies?

[JohnCockburn]

Based on my own experience, I'd say that it would be more accurate to say the wolf has been moved to a different note.

I'll add that I haven't run across any wolf elimination strategy, which doesn't change the overall character of the sound, and the impression of the change in sound is often negative.

 

David, does this mean that if one of your violins has a wolf note in this region you're happy to leave it, or do you have a "structural wolf avoidance strategy"?

[Peter K-G]

Based on my own experience, I'd say that it would be more accurate to say the wolf has been moved to a different note.

I'll add that I haven't run across any wolf elimination strategy, which doesn't change the overall character of the sound, and the impression of the change in sound is often negative.

 

You have to be very precise on spot and use a small weight. I couldn't do it alone and use real time FFT software to see visually when B1+ is lowered in dB without moving it's pitch.

 

This is an old tube on how I track the wolf

 

 

If you use too much weight B1+ is lower in pitch and B1- is altered too, as it also escalates in the same region.

 

When I do as described above the wolf is eliminated but C is still stronger because B1+ (and B1-) has the same pitch. The overall sound is not change but the violin is overall purer when the wolf is gone.

[jezzupe]

You have to be very precise on spot and use a small weight. I couldn't do it alone and use real time FFT software to see visually when B1+ is lowered in dB without moving it's pitch.

 

This is an old tube on how I track the wolf

 

 

If you use too much weight B1+ is lower in pitch and B1- is altered too, as it also escalates in the same region.

 

When I do as described above the wolf is eliminated but C is still stronger because B1+ (and B1-) has the same pitch. The overall sound is not change but the violin is overall purer when the wolf is gone.

Mommy, mommy make it stop!

 

Well I jive with lots of your ideas, some statements, maybe not so much, but....

 

Some questions, if you can make a wolf go away, is one correct in assuming that you could intentionally build one in? if so, it would be impressive to "create" 3 wolfs on three violins, and then make them all go away with your "idea", Which by the way I somewhat in agreement with, yet would point out that wolfs built into a new instrument are in my opinion a "contractor error" and or is something that obviously should be avoided and imo can be avoided.

 

I think a general broad statement could be made that wolfs are generally induced by an area being too thin in certain area/s and those thin spots are influenced by the thicker areas, some in the immediate location, some from further away.

 

Stiffness and mass generally go hand in hand. we need to not only think of flexibility as it relates to the stiffness, but also the mass and how more or less physical weight in any given area will react once excited, and once excited, how will it influence other areas.

 

A wolf is very much like ease dropping on two people trying to speak at the same time on the phone, someones flapping their lips when it's not there turn to talk and that there is a line that connects them, cut the line, they're both still talking , but you can't hear them talking over each other anymore.

 

The violin has certain elements to it that are like the old tin can/wire "phones" or walkie talkies, thick parts act like the cans,thin parts like the wire, but it's much more like a massive circuit board, lots of connections

[Peter K-G]

Jezzupe

If you read the OP and the link to my site you ser that I have reproduced the wolf on four violins in a row, plus on a re tuned old German factory violin. I could change my signature to Reproducing the wolf

This is precise work, see also modal goal on my site

[jezzupe]

These animations can be in my opinion very misleading. In any case B1+ peaks near lower bass f-hole and towards the middle. This is also shown from experiments on real violins (Stoppani/Kreit)

 

B1+ peak.JPGB1+ Kreit.JPG

 

SMAC 2013 Stoppani

2013_Acoustic_measurements_in_the_workshop.pdf

 

If you have a violin that Wolfs on C as described, a spot can be found when playing, preferable G string up high where it is horrible. Have someone near gently search for the spot with his finger and put a small weight there and the wolf is eliminated.

 

There is an opposite spot lower on the back plate, but that one needs a ~5 g weight and changes the sound (somewhat "squeezed") 

thanks for this link, I had not read this before, but It's nice to see many of my intuitive theory's finally being looked at, this guys all about structure, stiffness, bending and all that good stuff....

 

and thanks for the reply 4 violins, now that's impressive, I'll check it out...

[Doug Cotterill]

I have reproduced the wolf on four violins in a row

 

 

I usually get the wolf high up on the G string, around C, which goes away if someone touches between the bass sound hole and the chin rest. I don't try to eliminate it, in fact I would sort of feel disappointed if it wasn't there, and I move the wolf to between B and C by adjusting the tailpiece, so a player would have to play out of tune to hear it. Putting a cleat or weight inside may solve the wolf problem, but may deaden other notes nearby. To me, it's not worth that kind of fix.

 

I've never had a wolf on the other C's though, or anywhere else on a violin, so I'm surprised you can consistently do this. Maybe your plates are thinner than mine. My plates are a touch thicker than what's typical because they are low density, but then again I don't encounter wolf notes much on violins in general anyway. Great violins have them, or so I've heard.

 

I'd like to know how to make a cantankerous, difficult to play violin though, because there are some good players bragging about how hard their instruments are to play, on YouTube and in articles. It sounds like they are wrestling crocodiles, a real punch up, yet very satisfying somehow when the duel is over. I'd need to experience it myself I suppose to understand it. Probably good players would think my "hard to play" thing was bad, but if it was an old Cremonese thing, their opinion might be different.

[Peter K-G]

Doug,

 

B1+ is the root cause of this. From what you describe your violins B1+ has just about the strongness to wolf on G up high but not on D and A string. I'm not aiming at reproducing this wolf but when I optimize to a certain point B1 modes are very strong.

 

I guess if one wants to Reproduce The Strad Sound one has to reproduce their wolfs too 

[Doug Cotterill]

I haven't figured out the B1+ and B1- things yet, but I'm learning. The M5 and M2 are well known motorways here in Sydney.