Fifths tuning
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 (C-G-D-A 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 but increasing number of bassists, most notably American Red Mitchell and Canadian Joel Quarrington who now  is Principal in the London Symphony. Other players who use the tuning include Dennis Masuzzo, Silvio Dalla Torre, Paul Unger, Larry Holloway and Tomoya Aomori. Although still relatively uncommon (most fifths players are in Canada), its popularity is ever increasing. Its advocates say the advantages of fifths tuning are: