Original: The four key distinguishing elements of progressive bluegrass are ( 1 ) instrumentation , frequently including electric guitars , drums , piano , and more , ( 2 ) songs imported or styles imitated from other musical genres like jazz , rock and others , ( 3 ) non-traditional chord progressions , ( 4 ) lengthy '' jam band '' - style improvisation . However , not all these elements are always present in progressive bluegrass .
Simplified: The four important elements ( not always all present ) of progressive bluegrass are instrumentation ( usually including electric instruments , drums , piano , and more ) , songs imported or styles imitated from other musical genres ( like jazz , rock and others ) , non-traditional chord progressions , and lengthy '' jam band '' - style improvisation .