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Audio Distribution Amplifier - RB-MS4X3 17
Controls & Connectors
Front Panel
Fig 17-3: RB-MS4X3 Front Panel Connections
Ex48VDC
This latching push switch applies the ex48V phantom power (if
connected) to a microphone connected to the rear panel input connector.
ON LED
The ON LED illuminates when both ex48V phantom power is
connected to the rear panel DC socket and the external power is switched
to the input.
30dB Pad
It is possible to attenuate the incoming signal by 30dB for example when
interfacing a line level signal into a microphone preamplifier. The latching
push switch applies and removes the 30dB pad.
Important:
Phantom power should be disabled when connecting a line level
signal to the splitter input.
Ext.
Phantom
Enable
On Input
30dB
Pad
Phantom Loopback/
Ground Lift Output 2
Ground
Lift Output 3
Ext. Phantom
On Indicator
Output 2 Toggle switch
This switch controls both the grounding of the output 2 XLR connector
(pin 1) and the ability to pass back phantom power (via the internal
transformer’s centre tap) from output 2 to a mic connected to the splitter’s
input.
Switch Position
Phantom Loopback (PL)
Output 2 XLR Pin 1
Left
Disabled
Grounded
Centre
Disabled
Lifted
Right
Enabled
Grounded
Output 3 Toggle Switch
This switch controls the grounding of the output 3 XLR connector.
Switch Position
Phantom Loopback (PL)
Left
Grounded
Right
Lifted
Phantom Powering Guidance
It is possible to pass phantom power to the splitter input by three different
methods:
• Via the ex48V DC connector.
• From a mic pre-amp connected to direct output (output 1).
• From a mic pre-amp connected to output 2 (provided phantom loopback
is enabled).
It is therefore possible to concurrently power the microphone using any
two of the above methods (for power redundancy) without causing signal
degradation. It is important the output connectors are grounded (and not
lifted) should the external phantom power be connected, to prevent hum/
hiss caused by ground loop currents.
Important:
A maximum of two phantom powering methods can be used
concurrently.
