Tonal consonance theory assigns a level of dissonance to any pair of pitches played simultaneously. This theory connects timbre with tuning and proposes that tunings must use local minima of dissonance. The timbre of the marimba de chonta produces a broad minimum, a sharp maximum, and some sharp minima of dissonance. Here we show that the combined effect of the traditional tunings and the musical practices of this instrument only allows the use of the broad minimum, leading to special features of this music as a transposition practice that keeps geometrical distances instead of musical intervals.