Cut your cable to the desired length with the cutting side of a wire stripper tool. Strip one inch of the rubber sheath from each end using the stripping hole marked for 14 gauge wire. Be careful not to cut into the inner wires, which are just underneath the rubber sheath.
Separate the three inner wires at each end of the cable. Strip 1/4 inch from the insulated ends. The bare wire is usually wrapped around the other three. Gather the strands together with your fingers and twist them into a point to form a single multi-strand wire for soldering.
Open the housings of the XLR connectors by unscrewing the base or removing a small screw to gain access to the inner contact points. You will see that there are three contact points inside. Each contact point will have a number 1, 2 or 3 imprinted next to it.
Solder the bare wires to the number 1 contacts of each connector. Solder the red wires to the number 2 contacts and the black wires to the number 3 contacts.
Replace the connector housings after the solder joints have cooled for several minutes. Slide the casings back over the contact assembly and screw them back on, or secure them with the included screw, depending on the type of connector you purchased.