Redbox RB-DMX4 User Handbook
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INTR
ODUC
TION
INTRODUCTION
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RB-DMX4 4 x 4 Channel Digital Audio Mixer/Router
Introduction
Fig 1-1: RB-DMX4 Front Panel
The RB-DMX4 is a digital mixer capable of mixing or routing 4 mono input channels into 4
mono outputs, or 2 stereo inputs into 2 stereo outputs. The inputs are sample rate converted
to allow sources of different sample rates to be mixed. The flexible Mix Matrix allows for a
wide variety of mixing options and creativity, using 4 blocks of 4 way DIPswitches to select
which inputs are mixed or routed to which outputs.
The RB-DMX4 has 4 x digital mono audio inputs, each one selectable in pairs via front panel
INPUTS 1 & 2 and INPUTS 3 & 4 push buttons, from either AES/EBU balanced XLRs, S/PDIF
unbalanced phonos or TOSlink unbalanced optical inputs. Sample rate converters on each
input mean that sources of different sample rates can be used with the output sample rate
being defined independently. The colour of the INPUTS 1 & 2 and INPUTS 3 & 4 push-buttons
indicate whether the input source is synchronised (no colour) or not (flashing green and red).
Each input has a trim pot, which can be used to attenuate the input signal. This allows for
a perfect mix of channels at different audio levels. Audio presence LEDS around each input
button give an indication of input audio level. There is one LED for each channel. There are
also 4 presence LEDS around the MONITOR button which give an indication of output level.
Additional gain can be added by accessing the OUTPUT GAIN mode.
There are 2 stereo outputs which are available as simultaneous AES/EBU balanced XLRs, S/
PDIF unbalanced phonos or TOSlink unbalanced optical outputs. The output sample rates
are selectable via rear panel DIPswitches from one of 32kHz, 44.1kHz, 48kHz, 88.2kHz, 96kHz,
176.4kHz or 192kHz.
The unit has TTL wordclock BNC and AES/EBU XLR synchronising inputs as standard and
optionally, the RB-SYA and RB-SYD synchronisation boards can be fitted to synchronise
the unit to analogue or digital video signals. A rear panel DIPswitch block is used to decide
whether the unit is synchronised to Input 1 & 2, Input 3 & 4, the AES/EBU sync input, the
wordclock sync input or an optional video sync board. The DIPswitch block also selects the
synchronisation mode of the unit and the MONITOR button flashes whenever the unit is not
synchronised to an incoming sync signal. Selectable sync modes are as follows:
Master Mode
In this mode the digital output sample rate is simply set by, and locked to, the internal on-
board clock generator. No sync signal is used or required.
Auto Sync Mode
In this mode the digital output sample rate follows the selected sync input. When the sync
signal is not present the output sample rate will be set by, and locked to, the internal on-
board clock generator at the selected output frequency.