4
Redbox RB-DMX4 User Handbook
2
FR
ONT P
ANEL C
ONTR
OLS & INDIC
A
TORS
FRONT PANEL CONTROLS
& INDICATORS
INPUT 3 & 4 Source Select Button, Indicators & Input Presence LEDS
The operation of this button is identical to the INPUT 1 & 2 button but acts on inputs 3 & 4.
INPUT GAIN Pots
These pots allow the gain of each individual channel to be
trimmed so that the perfect mix can be achieved. Simply turn
anti-clockwise to attenuate the level or clockwise to restore it.
Fully clockwise is unity gain. Fully anti-clockwise is muted.
In Stereo Mode, pots 1 and 3 control the gain for channels 1 & 2
and 3 & 4 respectively. See page 7 for further information.
MONITOR Button & Output Presence LEDs
Normally, this button displays the external synchronisation
status and the four LEDS around it display output presence. If
the selected synchronisation source is unlocked, the button will
flash green and red. A button press allows you to choose which
channel is output through the headphone socket and to set-up
the output gain.
For monitor selection, the button illuminates red, as does the LED of the selected channel.
For output gain, the LEDS around the button illuminate in green sequentially indicating
the level of gain applied.
MONITOR Button Modes
The MONITOR button has three modes of operation with different functions: Display Mode,
Monitor Output Select Mode and Output Gain Mode:
Display Mode
Display Mode is the default mode of the button. In display mode, the four surrounding
bicolour LEDs act as presence LEDs for the output channels. Marked ‘1’ to ‘4’ , the LEDs give
an indication of the output level using the AES digital standard with the following colours:
-INF < -52dBFS = OFF
-52dBFS < -3dBFS = GREEN
-3dBFS <0dBFS = ORANGE
0dBFS/ CLIP = RED (AGC Operational)
Note re Clipping: The AGC is working on a channel if its output presence LED is red. The
mixing in this unit is achieved by the summation of 24 bit audio values. The total of this
summation could, if uncorrected, breach the upper limit of a 24 bit number, which would
lead to clipping. The unit detects these occurrences and adds an instantaneous attenuation
to bring the signal in range again. This attenuation factor will decrease on a slow decay
until 0dBFS is achieved, or until another breach occurs. The slow decay eliminates any
breathing or pumping effects in the audio.
If the unit is set to be synchronized externally but is not synchronized, the button flashes
green and red continuously. If it is synchronised, or the unit is set to MASTER sync mode,
the button is unlit.
Fig 2-4: RB-DMX4 INPUT
Gain Pots
Fig 2-5: RB-DMX4
MONITOR Button