Handbook

Table Of Contents
Redbox User Handbook No 3
33
Fig 5-5: Switch to Control LF Filter and Phantom Power.
Using Phantom Powered Microphones
For the input channel there are independent switches to provide phantom power at +48V
to the connected microphones. With phantom power selected, a voltage of +48V is applied
to pins 2 and 3 of the XLR connector to power the microphone, supplied through 6k8
resistors giving a current of 14mA. Phantom power is used when the switch is pointing
towards the arrow.
Using the LF Filter
A switch also provides control for a high pass lter with low frequency roll o at 125Hz. The
lter is in when the switch is in the down position (towards the arrow).
Output
The XLR 3 pin plug output connector is electronically balanced and can be wired
unbalanced by grounding the non-phase signal, allowing you to feed balanced and
unbalanced equipment. It has the following connections:
Pin 1: Screen
Pin 2: Phase
Pin 3: Non-phase
The connector provides a line level output with an impedance of <50Ω and a maximum
output level of +28dBu.
MICROP HONE AMPLIF IERS
& LIMITERS
On On
On On
2 3 4
1
1 Channel 1 Low Frequency (LF) Filter
2 Channel 1 Phantom Power
3 Channel 2 Phantom Power (only applies to MA2)
4 Channel 2 Low Frequency
MICROPHONE AMPLIFIERS & LIMITERS - RB-MA1 & RB-MA2
5