For the Union Army the best place to start is by reading Uniform and Dress of The Army of The United State, 1861: General Order, No. 6 War Department, Adjutant Generals Office Washington, March 13, 1861. This is often called to as Army Uniform Regulations of 1861.
Paragraph 14. "For All Musicians - the same as for other enlisted men of their respective corps, with the addition of a facing of lace three-eights of an inch wide on the front of the coat or jacket made in the following manner: bars of three-eights of an inch worsted lace place on a line with each button six and one-half inches wide at the bottom, and thence up, and contracting from thence to the bottom of the collar, where it will be six and one-half inches wide, with a strip of the same lace following the bars at their outer extremity - the whole presenting something of what is called herring-bone form; the color of the lace facing to correspond with the color of the trimming of the corps."