Apparatus for changing relative positions of conductor pairs in a cable core in which each pair is moved through its individual guide movable around a substantially circular path. The guides lie in series and move independently of one another. An array forming device at the downstream end of the movable guides has a smooth convex surface for engaging the conductors and holds them in an array while enabling the pairs to change their relative positions in the array as dictated by movement of the guides. A closing die for the conductor pairs is located downstream from the array forming device.