The Electric Bass Dead Spot

The Dreaded Dead Spot

Electric bass players have long endured a well known problem in their instruments called the dead spot. When played, the note decays quickly and doesn’t match the normal sustain of notes played on either side of the desired note. Typically found on the G string at the C, C#, or D note (5th,6th, and7th fret) and sometimes beyond, the severity varies, seemingly at random, from instrument to instrument, and sometimes appears to be completely absent. When comparing instruments (of the same make and model) the dead spot note as well as it’s severity can vary wildly. Problems with the dead spot make it difficult for the player to play slow passages evenly and to otherwise play with consistent volume, tone and intensity.

Dead Spot Terminator, Side View

Dead Spot Terminator, Top View

The Decay Pattern of the Dead Spot

The neck resonance, shown by the green trace, is at 140 hz. In the spectrum display above, C, C# and D are each played twice. While the center of the dead spot is just above C#, you will see and hear both C and C# dying away much faster than at D. It is very common for the dead spot to occur on several adjacent notes even though the neck resonance in this example peaks at 140 hz, just above C#. Occasionally the neck resonance will show as two adjacent peaks and the dead spot can spread to three adjacent notes.

The Dead Spot Eliminated by the Dead Spot Terminator DST-2

The same electric bass with the Dead Spot Terminator installed and tuned shows normal sustain on C, C# and D. The tuned resonators on the DST-2 prevent the neck resonance at 140 hz from absorbing the energy from the string, allowing the vibrating string to decay at a natural rate.

The Cause of the Electric Bass Dead Spot

The cause of the dead spot in electric basses, is a resonance in the neck which, when it coincides with the frequency of the note being played, absorbs the energy from the string and causes rapid decay in its vibration. There are many other resonances in the neck (and in the body itself) but the typical dead spot is caused by neck resonances in the frequency range of 130-150 hz. The other resonances in the body and neck do have an effect on the overall loudness and tone of individual notes, but don’t have the dramatic effect on the overall sustain as the resonance occurring at the dead spot.

However since every part of the bass vibrates when played, simple changes such as clipping a tuner onto the peghead, or moving from a standing position to a sitting position all have a significant effect on the dead spot frequency and severity. These details become important when taking steps to eliminate the problem.

Our solution to eliminating the electric bass dead spot is to attach a tuned resonant body (the Dead Spot Terminator) to the back of the peghead. In this position, the dead spot resonance is transmitted to the Dead Spot Terminator, causing the tuned resonators to absorb the vibration of the neck. By diminishing the vibration of the neck, the Dead Spot Terminator (DST) will then allow the string to vibrate and decay at a normal rate.

In contrast to the large body of research on the origins of wolf notes on the cello and double bass, as well as other resonances on string instruments, the research on dead spots on electric basses is minimal.The research by Helmut Fleischer (see reference page) stands out because his papers focus specifically on electric bass dead spots. Other researchers, such as Thomas Rossing and Fletcher cover dead spots in a more general way.

More importantly, there is little mention, in the literature, of any attempt to eliminate the electric bass dead spot, so the question of how to design a dead spot eliminator was an open question, Until now, the attempts at controlling the dead spot on electric basses have largely been to change the weight of the peghead. Due to the sensitivity of the neck resonances to changes in weight and stiffness, most of the time these attempts only move the frequency of the dead spot to another note or only reduce the severity. Once in a while, success is found, only to be defeated when trying the same technique on a different instrument.

It is interesting that the problem with dead spots seem to occur more often on basses with 34″ scale length necks, and that the problem varies with each instrument. Graphite necks, which are stiffer, and headless necks seem to have fewer problems. But for the vast majority of instruments built along more conventional lines, it is difficult to predict with any certainty whether or not a neck will have a dead spot.

Mentioned earlier is the fact that the dead spot resonance is just one of many resonances in the neck. The dead spot resonance is not the lowest resonance, but is, typically the second from the lowest (Fleischer, reference page). In some instruments the neck might have two or three resonances in the general area and may exhibit dead spots over a wider range than a single note.

The direction of movement of the neck vibration affects the preferred orientation of the Dead Spot Terminator. The neck could vibrate in plane with the fingerboard, perpendicular the fingerboard plane, or could twist (torsion) depending upon the characteristics of each resonance. Within any single resonance, the neck could be vibrating in multiple planes as well as with torsion. Clearly there is a lot more to be learned about neck resonances and how it affects tone and sustain, but the Dead Spot Terminator represents the state of the art in eliminating electric bass dead spots.

Installation, without modification of the peghead has been a priority in the development of the DST, and for the initial model, the DST has been designed to fit all Fender style basses with 34″ scale and with the tuner base attached to the peghead with four screws. The DST has been tested successfully on Music Man basses, and on basses with contemporary machines attached to the peghead with a screw on collar around the string post such as the Gotoh and Hipshot. For these basses, an adapter is in the works.

The Dead Spot Terminator embodies these exclusive features:

1. Easy installation using only a small phillips screwdriver
2. No modification to the instrument and unit hidden on the back of the peghead
3. Installation predictable with high confidence of success
4. Tunable frequency covers the normal dead spot note range (C to D# and beyond)
5. Guaranteed to reduce or eliminate your bass’ dead spot to your satisfaction