JACK

1)Segmented audio connector. Mono Jacks have two connections - tip and sleeve, and are unbalanced. Stereo jacks have three connections - tip, ring and sleeve. B-type jacks (also known as Bantam jacks) were originally designed for use in telephone exchanges and provide a high quality (and expensive) connection in jackfields. A-type jacks are cheaper and more common, but more fragile. A type jacks are available in 2 sizes quarter inch and eighth inch. 2) (US) A hinged brace. In the open position, it holds up a flat or other unit of scenery. A Tip Jack is a combinaton of a jack and castors so scenery can be supported or rolled. When it is in position, it is tipped to vertical. When rolling, it leans backwards.