Band Pass Filter Switch; Output To Telephone Balance Unit (Tbu); Output Level Adjustment; Operation Of The Rb-Mm1 - Sonifex Redbox RB-SS10 User Handbook Manual

11
GE N E R AL IN TERFACES

Band Pass Filter Switch

The band pass filter, when in the ON position, is used to limit the audio bandwidth of the
output to the TBU between 200Hz and 4kHz. When using the RB-MM1 in full bandwidth
equipment, e.g. for ISDN audio codecs, set this switch to the OFF position.

Output to Telephone Balance Unit (TBU)

The mono XLR 3 pin output plug connector is electronically balanced with an output
impedance of less than 50Ω. It has the following connections:
Pin 1: Screen.
Pin 2: Phase.
Pin 3: Non-phase.

Output Level Adjustment

The TBU output gain can be adjusted from -15dB to +12dB, ref 0dBu by using the LEVEL
preset potentiometer.

Operation of the RB-MM1

Before you receive your RB-MM1, it is calibrated at Sonifex by using two signals of equivalent
amplitude and frequency. In some cases it may require recalibrating for use on a mixer to
match the properties of that mixer. In order to do this make the following connections:
1. Mixer left output to the RB-MM1 left input .
2. Mixer right output to the RB-MM1 right input.
3. Mixer post fade output from the relevant input channel (usually telco) to the RB-MM1
telephone fader input.
Then apply a signal to the input channel and raise the fader to its maximum level. To get the
best results connect a level meter to the "Output to TBU" connector. Alternatively monitor
the output acoustically and tune by ear.
Then adjust the NULL potentiometer until the output is as low as possible, if there is still
some low frequency output adjust the LF NULL as well. The null available on this product is
>40dB at 1kHz.

Technical Specifications RB-MM1

Audio Specification For RB-MM1
Maximum Input Level:
Input Impedance:
Maximum Output Level:
Output Impedance:
Output Gain Range:
66
+28dBu
>20kΩ
+28dBu
<50Ω
Adjustable -15dB to +12dB, ref 0dBu gain via a multi-turn
pot
Redbox User Handbook No 3