Rev.7a (for units from ser.no. 51053/built 2010) 26.01.2010 This document substitutes previous versions page 10 of 34
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AIRCOM Manual
5.2.
Commentator Channels A and B
5.2.1.
Inputs and Configuration
Microphone inputs, XLR 3pole connectors labelled „MIC A“ and „MIC B“, are located on the rear panel.
Prior to connecting a microphone use configuration bank 1 in order to perform an input configuration
appropriate to your microphone.
Setting a switch to the ON position will activate the described function.
Function
MIC A
MIC B
Phantom power +48V
1-1
1-9
- 20dB Pad
1-2
1-10
LoCut 80Hz 24dB/Oct.
1-3
1-11
Limiter 1-4
1-12
Phantom power:
Only choose this option for microphones which are designed for operation
with 48V-phantom power. Otherwise there is a risk of damage to your
microphone.
- 20dB Pad:
Just in case you expect very high microphone levels. Also refer to section
“Gain Setting” (see below).
LoCut 80Hz 24dB/Oct.:
Frequencies below 80Hz are suppressed very effectively. Use depends on
speaker, microphone and environmental conditions. LoCut will also reduce
“pop noises” or low frequency interference caused by air condition systems.
Limiter:
Output level is limited to reference level. If selected, a green LED (LIMITER
ON) will light up on the front panel.
Note: Limiter configuration setting only affects the commentator channel
outputs. Intercom outputs are always post limiter.
Gain Setting
Set microphone gain at the gain trimmers labelled “MIC A” and “MIC B” on the front panel, left hand in
the configuration area. Always set gain with limiter off.
You can use the OVERALL ON AIR OUTPUT LEVEL to control your gain setting, if the respective ON AIR
button is activated. The O/L (Overload) LED at the right end of the display lights up if there is the
danger of signal clipping (1-2 dB below clipping), also refer to chapter 5.5.
In case your setting is fine with gain trimmer near its minimum (counter clockwise) and -20dB Pad OFF,
please consider:
Best S/N ratio is assumed with this setting. But if you expect high unpredictable levels, i.e. you need
maximum headroom, you should switch -20dB Pad to the ON position and on the other hand rise the
gain setting.
Limiter function
If a channel signal level exceeds reference level, the signal is controlled by the integrated limiter circuit
at the output (As the limiter provides a soft-knee technique, in fact signals somewhat below reference
level are controlled as well.). There is internal headroom of approximately 18dB before limiter.
Gain setting with Limiter
As described above, the limiter will to a certain amount affect levels below limiter threshold. If you set
gain with limiter activated referring to the “0” LED on the level meter, you give away some headroom.
So always set gain with limiter OFF, then switch it ON.
Please consider that a too high gain setting in combination with a limiter can lead to a loss of speech
comprehensibility. E.g. background noise may be audible in speech intervals.