Handbook

Table Of Contents
Redbox User Handbook No 3
65
GENERAL INTERFACES - RB-MM1
GENERAL INTERFACES
11
Front Panel Indicator
The LED on the front panel is normally red to indicate that power is present on the unit.
Rear Panel Connections and Operation
Fig 11-3: RB-MM1 Rear Panel.
Stereo Inputs From Mixer Main Output
These inputs should contain the main mixer output which will be a feed of the programme
plus the audio that you want to remove by the mix-minus unit. Ideally, the input should
be presented at 0dB. The XLR 3 pin sockets used for the left and right channel inputs are
electronically balanced and have an impedance of greater than 10kΩ bridging. Each XLR has
the following connections:
Pin 1: Screen.
Pin 2: Phase.
Pin 3: Non-phase.
Input From Mixer Telephone Fader
This mono input should contain the audio that needs to be removed by the RB-MM1, usually
from the telephone/telco fader of a mixing console. Ideally, the input should be presented
at 0dB. The XLR 3 pin socket used for the mono channel input is electronically balanced and
has an impedance of greater than 20kΩ bridging. The XLR has the following connections:
Pin 1: Screen.
Pin 2: Phase.
Pin 3: Non-phase.
Output Null Adjustments (LF and Full-Band)
The 2 x null preset potentiometers are used to adjust the null between the input from the
telephone fader and the main stereo input. The telephone input is made anti-phase and
used to cancel out that signal in the main stereo signal. So, the nulls adjust the level of anti-
phase signal required to achieve the best mix-minus null.
From Mixer
Main Output
From Mixer
Telephone
Output
Output
to TBU
Bandpass
Filter
Switch
Null Adjustment
LF Full-
Band
Output
Level
Adjustment