Wolf tones
Some thought on the cello’s wolf tones
Wolf tones are hyper-resonances that often occur with cellos. On some instruments they present no problem, but on others they make certain pitches difficult to play well. They typically occur in the area of Eb-F# on the G string (as well as the same pitches higher on the C string). If you are looking for a cello to buy or rent that has wolfs on the D or A string, just move on, this is not worth it. This is a sign of a poorly set up instrument.
With most wolf tones, it is possible to treat the wolf such that it is quite manageable. It is crucial to make sure that the setup is optimal first. If this is so, then there is one aspect of the setup to experiment with first that is not costly and can be effective, and that is the string afterlength. Typically the afterlength (the measure of the string from the bridge to where it is stopped at the end- usually the tuner) should be 1/6th the length of the sounding string length from the edge of the nut to the edge of the bridge. If the afterlength is more than that, it can make a wolf worse, if it is a bit shorter, that can make it less troublesome. If the length is “correct,” the bowed C string afterlength should sound approximately an octave above the open G string, so it you slightly lengthen the tailgut until it sounds F# on the C string afterlength, that can help.
If the wolf remains troublesome, the most common sort of wolf eliminator fits onto the string between the bridge and the tailpiece. In using these, first try it on the C string and tune it to the pitch a 5th above your wolf tone. You tune it by bowing the string between the bridge and the wolf eliminator. If that does not work, then try a 4th. If that does not work, try the note itself. The further away from the bridge you get, the fewer overtones you kill, which is why it is better on the C than the G. (There are 3 octaves of pitches on the other side of the bridge, BTW). If this is not effective enough, then try the G string.
Many people find the new Krentz eliminator much more effective and less problematic for the sound. Some people have reported that it can actually improve the sound of the cello.