This week one of my students ventured out to her first public jam session. She had previously jammed only at group lessons and at the FiddleStar/Murphy Method camp that we held last month. She has been playing just about a year and went to this jam with the intention of just vamping—not taking any leads. She was pleased to find that on most songs she could figure out what the chords were, by paying attention to the guitar player’s hands, and keep up pretty well.
She ran into a stumbling block on “Old Joe Clark.” They were playing it in A (that’s where it is always played), but because we banjos play it in G when there are no fiddles around, she wasn’t sure of the chords. She knew that when she played OJC in G the “off chord” is F. So when she tried to use that chord, only in the key of A, it sounded wrong. Someone leaned over to her and told her she needed a capo for OJC.
She wasn’t using a capo since she wasn’t playing lead, and a capo doesn’t make any difference to your vamping anyway, but it confused her. So here was the simple solution: when you’re vamping in A, you move everything up two frets from where it is in G. She had moved her regular chords up, but she forgot to move the off chord up, too! Problem solved.
Murphy Method Blog 
Casey,
I am still learning my around the banjo. What did you mean when you refered to the “off chord” and when is it used?
Thanks – Jim
LikeLike
Jim,
The “off chord” is the colloquial term for any chord that is not the usual G, C, D (or 1, 4, 5). In Old Joe Clark, the off chord is F. (Or G, if you’re playing it in the key of A.)
Best,
Casey
LikeLike