Polycom SoundStructure C16 Design Manual page 511

Because the AEC reference is available after the fader as presented in Introducing SoundStructure Design
Concepts and shown in the following figure, the result is that the AEC reference is also attenuated and
therefore the echo canceller would not be able to remove the echo because the reference level is attenuated
too much.
Output Processing
AEC
Reference
Parametric
Mute
Output from
Dynamics D/A Analog Output
or Graphic Fader Delay
Matrix
Converter Gain Signal
Processing
Equalization
The solution to this issue is to use the line output gain instead of the fader to attenuate the signal to match
it to the signal level requirements of the next piece of equipment in the signal chain. Changing these settings
are shown in the following figure. The result of this is that the proper signal levels are presented to the echo
canceller and the output signal levels are attenuated appropriately.
Polycom, Inc. 511