treble shift


A mechanical device on an accordion that directs air from the bellows through additional reeds to create a different tone quality of the melody notes. There are typically four sets of treble shifts, one set tuned in unison, a second set tuned one octave higher, a third tuned one octave lower, and the fourth set, the tremulant, tuned slightly higher than unison. A universal system of labels has been given to these treble shifts for the composer to designate specific sounds.

Table of Treble Shifts and Labels
Unison only
Unison only
Unison & Lower Octave
Unison and lower octave
Lower Octave only
Lower octave only
Unison & Higher Octave
Unison and higher octave

Higher Octave only

Higher octave only Unison and Tremulant
Higher Octave & Lower Octave
Higher octave and lower octave
Unison, Higher Octave & Lower Octave
Unison, higher octave and lower octave
Unison, higher octave and tremulant
Unison, lower octave and tremulant
Master (all sets)
Master, all sets

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