One of my favorite sounds is a chord pattern based on the changes associated with "Texas style" fiddling tune playing. This pattern will work with tunes like Sally Goodin', Sally Johnson, Katy Hill, and many others. I also find that parts of these patterns work nicely with Irish and Scottish reels & some hornpipes (not the exact pattern, but parts of).
I've put out similar patterns in the key of G and A which are similar with a few small exceptions. There are two chords per measure with each chord receiving equal time. Don't be afraid to substitute as there are an unlimited number of variations you can apply to these tunes. Use this pattern as a reference point and you'll be on your way.
Strings marked with an "x" are not played. Strings marked with an "o" are intended to be played. Pattern should read left to right and top to bottom. Important note: some of the chords may or may not be found in books exactly as I've written them. For example, I leave off the high "E" string on G7 and A7 and make it more of a "color chord."
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