Bosch DCN Next Generation Installation And Operation Manual page 258

258 en | Troubleshooting
Problem
–
–
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.
DCN-NG_IOM_V4.1 | V1.3 | 2012.07
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
Section 8.2 DCN-CCU2 and DCN-
CCUB2 Central Control Units).
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.
Installation and Operation manual
Hint
– The optical network cable that is
connected to the optical network
device is too long (refer to
Section 4.2.5 Cabling).
– More than the maximum nodes are
connected.
– Make sure that the audio input is
enabled with the control inputs (for
example, refer to
Section 6.3 LBB4402/00 Audio
Expander).
– The optical network does not contain
more than 16 devices (refer to
Section 4.2.2 Limits).
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
Section 7.3 DCN-CCU2 and DCN-
CCUB2 Central Control Units).
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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Conference System