Phonic MM 1805, User Manual

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conductors.(known as common mode signal) Because of the real signal is
carried by the 2 conductors out of phase, so it is perfectly carry to the input.
At the same time, the interference occurs during transmission will be
identical part (common mode), because the signal conductors are run
together, there is no chance they can be different, and all the interference
will be removed by the balanced input amplifier.
The difference in between 2 operations:
Because the common mode interference immunity of balanced system, and
at the same time, the ground conductor doesn’t need to carry any electri-
cal current so that it means the ground of the 2 connected units has identi-
cal ground level which is vital to interference free system.
Let’s look back to unbalanced system, the signal electrical current is from
signal conductor to ground conductor, and that means the ground level of 2
connected units are not identical. This means the system is much more
easier to be interfered with noise.
Running long cables is easy for balanced system but difficult for unbalanced
system, and the lower noise is always characterized in balanced system.
Because balanced system needs 2 conductors for signal and 1 conductor
for ground, minimum 3 conductors are needed for wiring balanced system.
So dedicated system separates ground and shield as 2 conductors.
Please read following section for proper wiring balanced and unbalanced
system:
The Correct Wiring for Balanced Operation
Always connect the main power with the 3-prong plug. Make sure the power
system ground is properly done. Don’t use ground insulator plug adapter
without properly connect the ground individually. This is vital to a successful
audio system connection.
Always connect the ground pin (PIN 1 in XLR) to the source unit, and
disconnect this pin at the destination unit. This connection topology is to
avoid grounding loop created by both connection of signal and power
ground. To utilize only the power ground, is because it always has lower
resistance and better distribution than signal ground.
If there is hum, the very possible reason is bad grounding connection in the
system. In case you can not find the fault, try to connect the ground pin of
the input connectors. If the hum is reduced or eliminated, check your power
grounding system. Special attention is needed when you use the equipment
racks with distance apart, and/or use large quantity of power amplifiers.
Check the power ground between the racks and power distribution strips
with your electricity engineer. Do make sure there is one and only one
proper ground point in the audio system (or connected video system.)