Headphone wiring conventions
The use of the word conventions may imply that there are standard ways of connecting headphones to 3 pole ‘A’ or ‘B’ gauge jack plugs. In a sense there are, but our investigations have uncovered a number of "standards" almost equivalent to the maximum number of possible ways in which the 4 terminals of a headphone can be connected to the 3 terminals of the connector! We have eliminated the most obscure methods, and show the four most common means of termination.
One point to note is that "Split feed" connection is almost exclusive to BBC users, and particulary those who have appropriately wired split feed headphone sockets, such as on many BBC local radio consoles.