Investigating Dead Spots of Electric Guitars

A long decay of the string vibrations of an electric guitar ("sustain") is considered as a quality attribute. In practice, there are particular locations on the fretboard where for one of the strings the sustain is shorter than at adjacent frets. The player calls this irregularity a "dead spot". It originates from the fact that the string causes the neck of the guitar to vibrate. As a consequence, energy flows from the string to the neck which results in a faster decay.

Three structurally different electric guitars (symmetric and asymmetric heads; neck screwed and glued to the body, respectively) served as measuring objects. In a first step, the decay times of the string signals were measured. In a second step, a technique was applied which allowed for in-situ measurements of the mechanical point conductance on the neck of guitars. The experiments revealed a clear inverse relation between the decay time of the string vibrations and the magnitude of the neck conductance. A local high neck conductance indicates a dead spot. In conclusion, the driving-point conductance, measured on the neck perpendicular to the fretboard, promises to be a key parameter for the diagnosis of dead spots.