Wolf Terminator

Wolf Note Eliminator for Double Bass

The Wolf Terminator is our answer to the problem of controlling wolf notes on the double bass.
Table of Contents

The Wolf Terminator for double bass, sharing all of the exclusive features of the Wolf Terminator for cello, has been developed specifically for the needs of the double bass player. The tuning range is F2 to A#2 which covers the wolf note range of most basses and the size has been optimized to eliminate the wolf without affecting the overall tone.

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Though most discussions regarding the control of wolf notes center around the  cello…… of no less importance to bass players is the elimination of wolf notes on the double bass.  As with the cello, the wolf note is caused by interaction between the note being played and the main body resonance of the bass. For the double bass, the wolf appears most commonly between G2 and A2, though the wolf can also be found occasionally beyond this range – below F2 and above A#2.  Basses will exhibit the wolf note prominently on the A and E string and, to a lesser extent, on the D and G strings as well.

The Wolf Note On The Double Bass

The Wolf Note (Between G2 and G#2 On This Bass)

The Wolf Terminator for bass is a technically advanced solution to the problem of controlling and suppressing wolf notes. It is easily adjusted to the exact frequency of the wolf note, giving precise control over the wolf and the loudness of the note relative to its neighbors on either side. The position of the Wolf Terminator can adjusted to give just the right amount of suppression with the least effect on the overall tone of the bass. And, just as importantly, pitch variation of the wolf note, because of string changes, setup adjustments, and seasonal variations is easily and quickly accommodated through small adjustments of the Wolf Terminators’ frequency adjuster.

The Wolf Terminator For Bass Is Adjustable for Pitch

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All of the design features, operating principles and adjustment procedures for the bass model are the same as for the (cello) Wolf Terminator, and everything regarding wolf notes in general  apply equally to the Wolf Terminator for bass. The tuning characteristics of the vibrating resonators encompass the wolf note range of the double bass and the size of the Wolf Terminator is adjusted to accommodate the bass”s physical size.

The Resonators Accommodate The Double Bass’ Size And Range

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The Wolf Terminator For Bass In Action

Installation And Adjustment

As discussed earlier, the wolf note is caused by interaction between the vibrating string and the instrument’s Main Body Resonance whenever their vibrating frequencies approach or become equal.  In figure 5 below, the Main Body Resonance is shown and in figure 6 the wolf note is shown when the string is played at the Main Body Resonance frequency.


(Fig. 5) The Main Body Resonance On The Bass

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On this 3/4 size bass, the Main Body Resonance shows a peak about midway between G and G#. at around 102 hz.  Of interest is the shape of the resonance curve for the bass which is broader than that for the cello.

(Fig. 6) The Wolf Note On The Double Bass

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The wolf note appears with two peaks. On the same bass shown in fig. 6, the wolf note straddles the main body resonance frequency and – on this instrument – is separated by 9 Hz. This gives rise to the stuttering or pulsing sound (in this case, pulsing at 9 times per second) characteristic of the wolf note. Situated midway between G and G#, the wolf, on this bass, affects both notes.

In figure 7 below, with the Wolf Terminator installed, the stuttering or warbling wolf note is eliminated. The note starts easily without the player having to fight for control.

(Fig. 7) With The Wolf Terminator Installed, The wolf Note Is Eliminated


After installing and adjusting the Wolf Terminator, the double peak of the wolf note is replaced by the single peak of a normal note. Since the Wolf Terminator can be tuned precisely to the frequency of the wolf note, the wolf can be suppressed without affecting the instrument’s overall tone. On this instrument, the G and G# now play normally.

Additional Benefits On The Low E

The wolf note which sounds on the A, D and G strings affects the playing characteristics of the E string in an important way.    The wolf note on the E string which corresponds to the wolf note on the A, D, and G strings,  appears high on the E string fingerboard, and is typically very pronounced. This E string wolf isn’t of particular concern to most players because the E string is not played in this range. What is very important, though, is the way the wolf note affects the same note an octave lower in the E string first position.

If, for example, the wolf note is G#2 (a very common wolf note frequency) at 103.8 hz, this would be the second harmonic of the G#1, at 51.9 hz, on the E string first position. Because the bass is less efficient at converting string energy into sound on the lower notes on the E string, the wolf note at the second harmonic has an outsized influence on the tone of the fundamental. You actually hear as much or more of the second harmonic than the fundamental. While the “classic” wolf note may not be as apparent, the presence of the wolf can give this area of the E string a muddy unfocused tone and add to intonation problems.

Because the Wolf Terminator can be narrowly tuned specifically to eliminate the wolf note at G#2, the installation and adjustment of the Wolf Terminator will also limit the second harmonic influence on the fundamental note at G#1. The result is a clean tone with focus, which also aids intonation.

Increased Sustain

With a properly adjusted Wolf Terminator installed, bass players who play pizz will also notice that, when playing notes at or near the wolf note frequency –  regardless of the string –  there is an increase in sustain. This is because the process of controlling the wolf note moderates the peak level of the main body resonance and keeps the bass body from absorbing all of the string energy at once when initially played. The string energy is absorbed more gradually, resulting in a slower decay rate and longer sustain.

The Robust Solution To Wolf Note Suppression