Fifths tuning is a non-standard tuning for the double bass, used primarily in classical and jazz music. In this tuning, the double bass is tuned like a cello, but an octave lower (C1-G1-D2-A2, low to high).
Although fifths tuning was once the most common double bass tuning in France in the 19th century, standard fourths tuning (E-A-D-G) has since become the most used tuning for the instrument. Fifths has recently been repopularised by a small number of bassists, most notably American Red Mitchell and Canadian Joel Quarrington.
Its advocates say the advantages of fifths tuning are: