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gle-ended 1/4" phone plug-equipped cable will work well and the balanced input circuitry will provide some
interference rejection, a balanced cable using either the balanced TRS 1/4" phone plug or the XLR plug will pro-
vide superior interference rejection and performance.
Sometimes, with difficult interference problems, it will be helpful to lift the shield ground ( Pin #1 of an XLR) of
a balanced cable at the RBN™118 Sub end. Check any input changes carefully, always turning the Gain control
down before plugging and unplugging cables, or lifting the ground.
Use of high quality, premium input cables is recommended for the RBN™118 Sub, as these usually have better
shielding and materials and will provide greater long-term reliability. The best option is a shielded balanced cable
no longer than necessary to reach the RBN™118 Sub. It is usually a good idea to leave some slack at the input to
the RBN™118 Sub and also to tape the cables down or run them under a cable guard to avoid anyone tripping
over them or pulling the RBN™118 Sub over when a speaker is mounted on the pole.
Gain Control Adjustment
The RBN™118 Sub is equipped with Gain controls (6) on the input to facilitate use in many different applications.
With the Gain control adjusted fully clockwise, gain is at maximum and the input sensitivity is 0.23 V RMS for
full-rated output with the line level position of the Mic/Line switch (7). When driving the RBN™118 Sub from
a mixer, it may be advantageous to reduce the input sensitivity by turning the Gain control to the halfway point.
The RBN™118 Sub will now more closely match a typical power amp.
If the mixing board indicates clipping of its output signals, then all of the RBN™118 Sub's power capability is not
being utilized cleanly. Clipping the signal before it gets to the RBN™118 Sub is not optimal. Reduce the mixer
output level and turn up the Gain control/s on the RBN™118 Sub.
The amplifier in the RBN™118 Sub is equipped with DDT™ and the LED indicator on the front baffle will show
when DDT™ has engaged. There is also an indication on the rear panel LCD display (12) that reads "DDT"
whenever the DDT compression system engages.
If the sound seems heavily compressed, check these indicators; if it is blinking RED more than occasionally, then
the drive level from the mixer (or the Gain control on the RBN™118 Sub) needs to be reduced.
When first turning on the sound system, switch on all upstream electronics first, then the RBN™118 Sub with its
Gain control fully counterclockwise (all the way down). Begin checking levels with the mixer output level con-
trols all the way down, and bring them up slowly with the RBN™118 Sub Gain control/s set to the
desired setting (one-third way up recommended to start).
It is not good practice to turn the Gain control/s on the RBN™118 Sub all the way up and then try to control level
only from the mixer, this approach would tend to pick up excess noise. Best practice would be to run a "hot"
signal from the mixer down the cable to the RBN™118 Sub, and then turn the RBN™118 Sub Gain control (6) up
only as much as necessary to reach full desired output. With this approach, it is necessary to verify the mixer
output is not clipping.
Disconnecting AC Power to the RBN™118 Sub
We recommend that the Power switch (1) be used to turn the unit off first, and then the AC power cord can be
removed, this minimizes stress to the power amplifiers and the transducers from turn-off transients. The pow-
er switch has an arc suppression capacitor to help during turn-off, and tends to make a clean disconnect from
the AC power, while the power cord IEC connector can make intermittent contact before finally becoming fully
disconnected, e.g., as when wiggling the cord.
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