I can bring it to a luthier and try to eliminate the wolf tone, but the previous owner, a professional violinist, played the instrument for 15+ years, so I guess they tried to remove it and failed.
Assuming it can't be fixed, would you buy such an instrument for a student, even an advanced one? Or would it hinder his progress?
Tweet
If you’re considering a purchase, the violin should be in adjustment and working as you need it before the money changes hands. If you buy hoping for a solution later it could be a huge mistake. If the wolf cannot be eliminated with skilled adjustment, that suggests the violin has a significant problem that could be shockingly expensive to deal with.
With cellos, wolves are much more common, and many players must choose between having them moved to a less problematic spot through adjustment or changing bow attack for the exact notes to play through them. Violins don’t usually have wolves, so the appearance of one is often the sign of a structural issue or an error in setup.
Two things to keep in mind:
1) Adjustment will change the sound of the instrument overall. This may be an improvement or a setback. Violins are delicate systems that are all interconnected, so it’s just about impossible to make an isolated change that doesn’t impact the other aspects. If the instrument isn’t working as it should, the odds are good that adjustment and elimination of the problem will be better for the violin overall (assuming the cause isn’t structural).
2) If the violin is on trial, any changes to its setup should be done with clear permission from the owner. While a violin should perform as you need it before you buy it, you can’t necessarily assume the way you like it adjusted will appeal to anyone else, so if you return it having been adjusted, the owner may need to undo the changes to make it ready for sale again. This is one case where it is not better to ask for forgiveness than for permission, as the latter is much more likely than the former.
ALL violins have wolf tones. If you say yours doesn't, bring it to me and I WILL find it.
Obviously, some are worse than others, but in the end, even if you can't eliminate a wolf, all violins are a compromise. If you really like the tone and response and dimensions, you might have to live with a wolf.
In my opinion, I wouldn't try to completely get rid of the wolf because you risk losing overtones. I would try and tame it a bit so that it's still there, but easy to deal with. Luthiers and top musicians have shared this same opinion. Just talk to whoever is selling the violin about it. If it's a shop, they should have no issue dealing with the wolf, and if it's a private sale, you could go to the luthier together and make sure that it's working just the way you want it to before purchasing it.
My luthier (died one month ago) always said that great violins have a wolf note.
I have violins with a wolf, and it never stopped me to play them.
On the contrary, I believe that having to deal with a possible uncertain note, due to a wolf tone, forces me to put a particular care in sound production, and so in the end it could be formative instead to be seen as a limitation.
While there are adjustments and add-ons that can reduce or eliminate the wolf, I don't know of any that a high-level player wouldn't find detrimental to the overall sound.
A crude example:
Submersing a violin in water will eliminate all wolfs within the human hearing range, but the violin won't sound very good or project very well. ;-)
I’ve heard the rumor that great violins have wolves floating around in the last few years, but I think that’s a modern idea. It may also be tied to the more aggressive playing style that’s become popular and the combined use of higher tension strings and tight soundposts. It’s possible for one to appear if there’s a significant change to the setup that puts things out of balance or a structural problem that’s changing the output of the violin’s air volume. If one exists from the start, it’s considered a mistake by the maker.
That reminds me of a violin that came in at a shop where I worked previously. It was bought directly from the maker. Upon arrival it was set up with its original parts and played. Despite the maker having made many fantastic instruments in the past, this one just did not play well at all and it had a bad wolf on the open A. The owner of the shop gave it a new setup to see if the wolf would go away, but to no avail. That was the last violin the shop ever bought from the maker.
This is not to suggest that a violin having a wolf can automatically be taken as superior. And yes, I can make pretty much any violin wolf if I try, because I know how to do it, but I don't think this is what we're talking about here.
Violinist.com is made possible by...
Dimitri Musafia, Master Maker of Violin and Viola Cases
Johnson String Instrument/Carriage House Violins
Discover the best of Violinist.com in these collections of editor Laurie Niles' exclusive interviews.

Violinist.com Interviews Volume 1, with introduction by Hilary Hahn

Violinist.com Interviews Volume 2, with introduction by Rachel Barton Pine
On the other hand, many fine violins have a wolf note and expert violinists learn to deal with it, I'm told; modifying playing techniques, etc. I think there's a video of Hilary Hahn practicing and sounding a wolfy-tone, trying to work with it.
There may be trade-off issues; a violin could have so many other good qualities, you deal with the bad as well as the good. My opinion/preference is maximize the learning experience for a student, don't insert roadblocks to their progress where you don't have to. Is a wolf note an impediment or a challenge? You tell me... -)