Gain And Dsp Processing; Input Signal Chain (Microphones) - Extron electronics MediaPort 200 User Manual

Gain and DSP Processing

The templates provide the necessary routing as it applies to Applications #2 and #4
described in the Audio Application Setup section on page 1 of this user guide, as well
as control hooks for use with a control system. Certain processing blocks have also been
pre‑configured within the DSP Configurator templates. Adjustments may be needed for
specific source devices and microphones, while gain settings will need to be made to
achieve optimal gain structure. Extron Building Blocks can be used to configure any of the
following signal chains for gain and processor settings (see the DMP 128 User Guide or
DSP Configurator Help File for information about Building Blocks).

Input Signal Chain (Microphones)

Microphone input channels contain basic filter and compressor processors for microphone
signals. Eight microphone channels are configured. Unused channels can be reset to
defaults, or hidden.
Gain
The default input gain setting is 0 dB, muted, with phantom power off. Gain and phantom
power must be set for each individual microphone, according to mic sensitivity, mic type,
proximity to the talker, talker characteristics, etc. Extron Building Blocks will make these
settings for an extensive list of microphones. See the DSP Configurator Help File for more
information on inserting Building Blocks.
Wireless microphones typically have a line level output. A setting of 0 dB may work for a
balanced, pro line level output of +4 dBu, while an input gain setting of +11.8 dB will bring
an unbalanced, consumer level output of −10 dBV up to pro (+4 dBu) line level. Some
additional adjustment may be necessary, depending on the talker and other settings on the
mic receiver.
Filters
A high‑pass filter is present to attenuate rumble and pops. A bass and treble filter is also
inserted, but with no gain settings.
Dynamics Processing
A compressor is present with a gentle ratio and high threshold that will engage the
compressor at higher gain levels. This will have the effect of normalizing the microphone
levels for louder talkers.
AEC and Automixer
AEC and Automixer are processors that are essential to conferencing. These processors are
not part of the Building Block set of input processors, and will remain unaffected if Building
Blocks are used.
The AEC is set to a reference channel that is part of the template configuration, and
should not be changed. If input gain and reference levels are set properly, often no further
adjustments to the AEC settings will need to be made.
An Automixer has been inserted into the mic input signal path, controlling the number of
microphones that can be open at any time during a conference. The use of an automixer
will greatly contribute to intelligibility. The default settings are used. Therefore, it should
be verified that microphones are turning on at the proper time while the system is in use
or being tested. If microphones are not gating on and off properly, adjustments to the
threshold and other parameters may need to be made. For more information, see the
DMP 128 User Guide.
MediaPort 200 Audio Application Tutorial • Configurations for DMP 128 30