6 string Double Bass; does it exist? | TalkBass.com
Sonata for Double Bass and Six String Electric Bass - YouTube
Double bass - Wikipedia
Upright Basses — Jordan Violins
Bruce Sexauer's "The String Bass (.com)" offers a wonderful example of American Enginuity, Dalton Dillingham's 6 string "American Standard" double bass.
Upright Basses — Jordan Violins
Double bass - Wikipedia
6 string bass hi-res stock photography and images - Alamy