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XLR shells
109
XLR shells
XLR pin 1s should only be used to provide a ground connection for cable screens. The
shell (body) of cable XLRs also need to be connected to ground so they provide a screen
for the terminals, but they should not be wired internally to the pin 1 terminal. Their
ground should be prevented from contact with the panel XLR connector body. This is
particularly important for unbalanced connections where an internal connection from
pin 1 to the connector shell could compromise ground lifting schemes. With this wiring
arrangement, joining XLR cables together to increase the overall length is best avoided,
because the joint will not be properly screened. However, if absolutely necessary it is
unlikely to cause major problems.
Signal ground bonding
If an unbalanced connection is required to external equipment with signal grounds that
cannot be isolated from safety earth it will be difficult to eliminate ground loop currents,
but their effects can usually be reduced. The currents within a ground loop will
generate small voltages in the cables, including the signal grounds. Any voltages that
develop in the signal grounds will appear as noise errors in the audio. If the impedance
of the screen cables is reduced, the voltage developed by the ground loop will also be
reduced. So, if the impedance can be zero there will be no noise. This is difficult to
achieve, but ground bonding the external equipment rack to the chassis of the VeniceF
will have a similar effect and will significantly reduce noise in unbalanced connections
between the two locations. A binding post chassis ground is provided on the VeniceF
for this purpose.
VeniceF
Operator Manual