Watch the Comin' Round the Mountain online guitar lesson by Stephen Mougin from Bluegrass Rhythm Evolution
Now let's break down "Comin' Around the Mountain". Jimmy Martin discovered that by adding an extra upstroke, he could add a lot more forward motion (or drive) to his ensemble sound. In addition, he tended to play more than one note on the downbeat and eliminated the second plucked bass note in favor of a strum.
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