Installation manual

Engineering - 28
Installation of dBX 1024 Buffer Amplifier
The dBX 1024 Buffer Amplifier is used as an impedance matching device between SMARTCASTERS
with unbalanced input and outputs, and the console. Similar to a dBX 140, but without companding
capabilities, it is often used with systems containing high quality audio cards. The dBX is also used to
match levels and provide balanced inputs and outputs. Like the dBX 140 unit, the Buffer Amplifier can
match both an unbalanced Hi-Z input to a balanced 600 ohm output and match a balanced 600 ohm input
to an unbalanced Hi-Z output.
In cases where the SMARTCASTER has stereo Simultaneous Playback and Record, two dBX units are
needed. This is because a Simultaneous unit has two outputs - “Audition” and “Air.” (Thus, one can
listen to a commercial just recorded via Audition while other spots are going over the air via the Air
output.) With two stereo outputs, two stereo dBX decoders are needed. As a result, the second dBX unit
is just used for output only.
Mounting
The dBX unit(s) may be rack mounted using the mounting kit that is included, or it may simply be set in
any convenient location near the SMARTCASTER. (Refer to the dBX manual for instructions on the
rack mounting kit.) Note however that since the SMARTCASTER connections to the dBX unit are
unbalanced, the leads MUST BE AS SHORT AS POSSIBLE! Please take care that the unit is not near
any sources of RF that might interfere with its operation.
Connections
Rear view of dBX 1024
The dBX 1024 uses locking XLR connectors for balanced, 600 ohm connections, and RCA phono jacks
for unbalanced HI-Z connections. The XLR jacks are wired pin 2 HOT (+), pin 3 COLD (-), and pin 1
chassis GROUND. Since the RCA connects are unbalanced, the outside conductor is Ground, and the
remaining conductor is HOT (+).
Depending on the type of system to be installed, there are several configurations for wiring the Buffer
Amplifier. Simply pick the appropriate diagram below and wire accordingly: