or a DIN cable. For mono interconnections, the 3/180° plugs are sufficient. When a mono plug is inserted into a stereo socket, it mates with the left channel. For playback only interconnections, the 3/180° plugs are sufficient, with pin 1 and 3 used for the stereo channels and pin 2 as signal ground. Five-pin DIN inputs for record players and auxiliary signal sources commonly join pin 1 and 5 in order to be compatible both with the 3/180° and 5/180° pinouts. This generally works fine. However the join of pin 1 and 5 on adapters between DIN and RCA connectors can cause problems if used with a five-pin DIN connector tape connector on an amplifier or receiver, as it will join the left record with right playback signal. The other way around is usually not a problem as sending the right playback out of a tape recorder back in to the left record input usually imposes no problem in playback mode. The signal levels are generally in the low range of line levels for playback/reproduction signals. The levels for recording can be considerably lower, more like microphone levels in some cases. Some manufacturers, like Philips, Uher and others, did use the connector slightly differently for tape recorders. Pin 2 (signal ground) was the same as others, and in playback mode pin 3 and 5 were used for left and right line level output as others. However in record mode all pins were active inputs, with pin 1 and 4 for low-level signals like microphone levels, while pin 3 and 5 were used for line-level signals. On all these recorders the output signals were only active in play mode, not in stop, record, rewind, fast forward or any other mode. The main benefits with this usage is that tape copying can be done with the regular pin-to-pin connected cables commonly used to connect tape recorders to amplifiers/receivers. An additional benefit is that several tape recorders can be connected in parallel, and can also be connected to an amplifier/receiver. Copying is done simply by pressing play on the playback recorder, rec on any recorders used for recording, and the amplifier/receiver is either switched off or set to the tape position. Recording of radio broadcasts or records is equally simple, just press record on any recorder and do not set any other recorder to playback mode. This eliminates the need for any switch