Three instruments that have a great capability to elicit deep blue feelings are the violin, viola and cello. I'll grant that not too many would fancy toting a cello around, but no other instrument I can think of, save the trombone, can "bend" a blue note quite as well. I have always been curious as to why these strings "need not apply" for the blues, in all but a handful of cases. Maybe we're on to something here...