A speaker's wire plugs are generally red (positive) and black (negative). Red wires connect to red plugs, and black wires connect to black plugs. If a speaker's wires contain different colors, the wires should be matched to their plugs by their positive and negative symbols. Full Answer >.
Finding wall studs. Wall studs in modern homes are spaced 16 inches on center -- that is thedistance from the center of one wall stud to the center of the next is 16inches. In older homes, studs may be 24 inches apart, or spaced irregularly.
A 2x4 stud with the same loading as above but spaced only at 16 inches does not calc. Shorten that stud to 8 feet long and it makes it, but barely. To get a 2x4 to calc at 24-inch spacing, it can be no longer than 9 feet and support only roof load.