Bosch DCN Next Generation Operation Manual page 260

260 en | Troubleshooting
Problem
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Acoustic feedback
Acoustic feedback ('howling') occurs when the sound of the loudspeakers or headphones in
the system is sent to the system again by enabled microphones.
Source
The acoustic feedback is
caused by the
loudspeakers of the
contribution devices.
The acoustic feedback is
caused by an external
public address system
that is connected to the
DCN System.
The acoustic feedback is
caused by the
headphones that are
connected to the
contribution devices.
2013.11 | V2.0 | DCN-NG_OM_V4.x
The display of an optical network device
shows No Network.
The audio inputs of an optical network
device do not give an audio signal.
Quick solution
Decrease the volume level of
the system. For example, with
the knob on the front of the
central control unit (refer to
DCN-CCU2 and DCN-CCUB2
Central Control Units, page
231).
Decrease the volume level of
the public address system or
the DCN System.
Tell the chairmen and the
delegates to decrease the
volume level of their
headphones with their
contribution devices.
Hint
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Operation Manual
Conference System
The optical network cable that is
connected to the optical network
device is too long (refer to Cabling,
page 80).
More than the maximum nodes are
connected.
Make sure that the audio input is
enabled with the control inputs (for
example, refer to LBB4402/00 Audio
Expander, page 117).
The optical network does not
contain more than 16 devices (refer
to Limits, page 77).
Do as follows: 1 Install a
feedback suppressor between
audio input 2 and audio output
2 of the central control unit. 2
Set the audio routing mode of
the system to Insertion (refer
to DCN-CCU2 and DCN-CCUB2
Central Control Units, page
183).
Install a feedback suppressor
between audio output 1 and
the input of the external public
address system.
Install and configure the
headphones level reduction of
the contribution devices.
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