DAS Dynamics Serie Manual Del Usuario página 23

APPENDIX A. Line connections : unbalanced and balanced
There are two basic ways to transport an audio signal with microphone or line level:
Unbalanced line: Utilising a two-conductor cable, it transports the signal as the voltage between them. Electro-magnetic interference
Phono
can get added to the signal as undesired noise. Connectors that carry unbalanced signals have two pins, such as RCA ( ) and ¼"
(6.35 mm, often referred to as jack) mono. 3-pin connector such as XLR (Cannon) may also carry unbalanced signals if one of the pins
is unused.
Balanced line: Utilising a three-conductor cable, one of them acts as a shield against electro-magnetic noise and is the ground
conductor. The other two have the same voltage with respect to the ground conductor but with opposite signs. The noise that cannot
be rejected by the shield affects both signal conductors in the same way. At the device's input the two signals get summed with
opposite sign, so that noise is cancelled out while the programme signal doubles in level. Most professional audio devices use
Cannon
balanced inputs and outputs. Connectors that can carry balanced signal have three pins, such as XLR ( ) and ¼" (6.35 mm)
stereo.
The graphs that follow show the recommended connection with different types of connectors to balanced processor or amplifier
inputs. The connectors on the left-hand side come from a signal source, and the ones on the right hand side go to the inputs of the
processor or amplifier. Note that on the unbalanced connectors on the left-hand side, two terminals are joined inside the connector. If
hum occurs with balanced to balanced connections, try disconnecting the sleeve (ground) on the input connector. Note that the
illustrations show what should be connected to what, but that pin locations on an actual XLR connector are different. Also, pin 2 hot is
assumed on XLR connectors.
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