BSS Audio FDS-318 Owner's Manual - Manual (Page 15)

15
9.0 Audio Connections
The FDS-318 audio inputs are RFI filtered and electronically balanced, with the
outputs electronically balanced and floating. They are designed to operate at
any signal level up to +20dBu and will drive into loads of 600 ohms or greater.
Refer to figure 9.1 for the wiring convention. 9.1 Wiring
convention
Audio connections
Fig 9.1 XLR Plug Wiring
9.2 Balanced wiring Whether your system is wired to a 'Pin 2 hot' or a 'Pin 3 hot' convention is not
important, so long as the wiring to both input and output 3 pin XLR connectors
is the same. As is common with all other BSS Audio equipment of this type, we
follow the convention of 'ground goes forward with the signal'. Input cabling
screening therefore needs to be derived from the signal source end as Pin 1 is
ground lifted for the inputs. It is recommended that you use high quality audio
cable with 2 cores and a screen for low noise and reliability.
9.3 Unbalanced
wiring
If the equipment driving the FDS-318 has only unbalanced outputs, then you
will need to add a wire jumper such that the screen connection on Pin 1 of the
XLR is shorted to either Pin 2 OR Pin 3, depending on the wiring convention of
the unbalanced equipment.
If the equipment being connected to the FDS-318 outputs have only
unbalanced inputs, then we recommend that you still use a balanced (I.e.: 2
core shielded) cable. The interconnecting cable should have its screen
grounded by Pin 1 of the FDS-318 output, and Pin 3 output should be
connected to the unbalanced input 0V ground. The Pin 2 output should be
connected to the live input. There should be no connection between the cable
screen and 0V/chassis ground connection of the unbalanced equipment. Strict
adherence to this will help to eliminate potential ground loop hums by
removing signal currents from the cable screen.