Series R y ST. Manual de Usuario /
R and ST Series. User's Manual
77
10. APPENDICES
Appendix A. Line connections : un-balanced and balanced
There are two basic ways to transport an audio signal with
microphone or line level:
Un-balanced line: Utilising a two-conductor cable, it
transports the signal as the voltage between them. Electro-
magnetic interference can get added to the signal as
undesired noise. Connectors that carry un-balanced signals
have two pins, such as RCA (
Phono) and ¼” (6.35 mm, often
referred to as jack) mono. 3-pin connector such as XLR
(
Cannon) may also carry un-balanced 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 balanced inputs and
outputs. Connectors that can carry balanced signal have three
pins, such as XLR (
Cannon) 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 un-
balanced 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.
www.audiovias.com
