SoundCraft Audio Mixing Console Model Spirit Studio - Manual (Page 9)

used in several configurations as shown in the dia-
grams below.
Balanced and Balanced and
Unbalanced Unbalanced
All channel inputs are balanced, i.e. there are separate
+ve(hot) and -ve (cold) wires for each signal plus a
ground. The design of the differential input amplifiers is
such that interference picked up on these wires is can-
celled out. This is because, since both wires are in
close proximity, the same interference will be picked
up on each wire and balanced input amplifiers will only
amplify the difference between +ve(hot) and -ve(cold).
Any signal on both hot and cold (i.e. noise) will not be
amplified - this is known as common mode rejection
(CMR.). If using an unbalanced source into a balanced
input, it is a good idea to connect the source ground to
the negative input. Should the source device have no
connection to mains ground, then connect the shield at
both ends. If there is a connection to mains ground,
then the shield should only be connected to the source
device ground.
Note: many modern audio/musical instruments have
electronically balanced outputs which should not be
unbalanced by shorting one wire to ground. Always
use your inputs balanced where possible.
The mix, group and auxiliary outputs are ground com-
pensated and provide a very effective way of
optimising noise immunity, without the cost and com-
plexity of balanced outputs. These outputs employ
ground compensation techniques to cancel out the ef-
fects of variation in ground potential between the mixer
3 POLE (stereo) JACK 2 POLE (mono) JACK
Tip
Ring
Sleeve
Hot(+ve)
Cold(-ve)
Screen
Left Signal
Right Signal
Ground
Send
Return
Screen
Signal
Ground
Tip
Ring
Sleeve
Insert Points Line Input
Aux Outputs
FX Returns
Headphones Unbalanced
Input
Page 7