DAS Vantec Series - Annex; Line Connections: Unbalanced and Balanced

36 Vantec series User's Manual
Vantec Series | Annex
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. Electromagnetic interference can get added to the signal as undesired
noise. Connectors that carry unbalanced signals have two pins, such as RCA (Phono) and ¼”
(6.35mm, 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
electromagnetic 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 balanced inputs and
outputs. Connectors that can carry balanced signal have three pins, such as XLR (Cannon)
and ¼” (6.35mm) 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.
Balanced XLR (Cannon) to Balanced XLR
Unbalanced XLR (Cannon) to Balanced XLR
Balanced 1/4" (Jack) to Balanced XLR (Cannon)
Unbalanced 1/4" Jack to Balanced XLR (Cannon)
RCA (Phono) to Balanced XLR (Cannon)
Balanced 1/4" (Jack) to Balanced 1/4" (Jack)
Unbalanced 1/4" (Jack) to Balanced 1/4" (Jack)
RCA (Phono) to Balanced 1/4" (Jack)