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Wolf tone eliminators - how do they work?

Discussion in 'Setup & Repair [DB]' started by Martin Beer, Dec 10, 2013.

  1. My bass has a terrible wolf tone around the octave A on the A string when played arco, which also happens to a lesser extent on the same note on the D string. It's an un-named flat back carved German bass with Spiro Mittles. I've been playing a little more around the octave lately, so I tried a wolf eliminator to sort it out, the Lup-X brass variety.
    The afterlengths on my bass are an octave and a fifth above the open strings, and I found I got the best results with it on the A string afterlength and placed so that the string between the wolf eliminator and the tailpiece was also pitched around A. This has flattened out the wolf tone almost completely, with a small but not unpleasant change to the tone across the rest of the bass.
    So, this would seem to be a success, but I'd like to understand a little about what the weight is actually doing. Is the vibration of the weight absorbing some excess energy at this frequency, or is it more complex than that?
  2. tappingtrance

    tappingtrance Cooke Harvey Supporting Member

    Jul 27, 2005
    I would like to know as well, horrible Bb on D string.
  3. dperrott


    Oct 3, 2005
    I know some one who has a rubber ball (like a kids toy ball) lightly wedged between the tailpiece and the face of the bass. She says that works. I have no idea where her wolf tone is/was. I went to a product demo from thomastic strings. I think he said, you could put a heavier string on, and that may remove it or possible relocate it.


    Mar 4, 2008
    Larisa, Greece
    I have exactly the same wolf tone in a recently aquired bass, around the octave in the A string. Since the instrument is a brand new one i didn't try so far to tame the wolf tone, waiting for it to be acclimatized in it's new environment. Nevertheless either a brass ball or a Marvin wire tailpiece have worked miracles in past cases, so i'd like to hear any plausible explanation!
  5. powerbass


    Nov 2, 2006
    western MA
    my bass has an Ab wolf tone, Marvin tailpiece and a wolf tone eliminator got rid of it. electric basses have wolf tones too, due to the resonate frequency of the bass. adding or subtracting weight messes w/this dynamic.
  6. fdeck

    fdeck Supporting Member Commercial User

    Mar 20, 2004
    Madison WI
    HPF Technology LLC
    The frequency of a resonance such as a plucked string depends on the mass and the tension. Adding mass to one of the afterlengths doesn't make it stop vibrating, but makes it vibrate at a lower frequency that is hopefully not sympathetic with any other resonances in the instrument.
  7. So that would suggest that the afterlength vibration was the root cause of the problem, and altering the frequency of that vibration takes it out of the problem range? I also wondered whether the wolf could be a product of the string vibration interacting with another mode of the instrument, and the weight created another resonance at that frequency to somehow absorb that vibration.
    I'm genuinely curious about this, and some searching turned up this paper; http://mafija.fmf.uni-lj.si/seminar/files/2010_2011/ViolinWolf.pdf
    The physics are a little above my head (I'm a chemist by training), but the explanation of wolf eliminators presented on page 16 does seem to fit with how my bass behaves with a wolf eliminator in place. In particular, because I find that the wolf eliminator works effectively in one position only, this suggests to me that I have to tune the afterlength/weight assembly to a specific frequency for it to work, rather than de-tuning it away from a specific frequency.
  8. Co.


    Sep 10, 2006
    Exactly. I got rid of a very "wide" wolf (G-G#), by tuning the afterlength of one string close to the same note and using a havy weight brass wolf eliminator on another string. Both have to be tuned very precisely to work 100%.
  9. powerbass


    Nov 2, 2006
    western MA
    electric bass guitars typically have a dead spot/note around C on the G string. an engineer at Fender Guitars in the 1960's worked on this issue using a steel neck and then developed a headless bass. the design didn't catch on. you can read more about this if you google it-the article is on a vintage guitar site. the point is altering the mass of a stringed instrument has a noticeable effect