Extron Electronics MPX Plus 866 A Rev. B - Manual (Page 143)

5-37 MPX Plus 866 A Media Presentation Matrix Switcher • Switcher Software
PRELIMINAR
Y
Setting the input and output gain structure
Before calibrating loudness, set up the system gain structure.
1 . Set the signal generator to output -10 dBFS or use recorded program material
at -20 dBFS.
2 . Set the input gain in the DSP Configurator so that the input meter reads
-20 dBFS.
N In step 3, if using a recorded source and the player has an output level setting
control, ensure that the output of the player is set to its maximum, or 0 dB of
attenuation.
3 . For program material, set the input level to approximately -15 dBFS, with
peaks at no more than -5 dBFS to -3 dBFS. This setting provides enough
headroom to accommodate transients or unanticipated loud events in the
program material in order to avoid possible clipping.
4 . Tie the audio from the source to the speakers that will carry program material
in the room to be calibrated.
5 . With the output channel volume set to -20 dB, listen to the audio output while
you set the external amplifier so that the source material plays at a volume
level that is reasonably loud but tolerable, while verifying that the amplifier is
not clipping by observing the amplifier clip indicator.
Adjusting the pre-matrix
The pre-matrix trim control can be used to compensate for any level changes caused
by signal processing before the trim control. Adding a compressor generally
reduces the signal level, while a filter can either boost or cut the overall signal level.
N This procedure is valid only if no processing is active in the output signal path,
and if post-matrix trim value is set to 0 dB (unity gain). If you have processors
inserted in the output signal path, open them and bypass them to temporarily
remove them from the signal path.
1 . After you have set the input gain, add any processors that you wish to use
into the input signal chain.
T If you make changes to filter settings after you have set your dynamics processors,
recheck the levels in your dynamics processors to make sure that they are still valid.
2 . Open the line input gain dialog box, the output volume dialog box, and the
pre-matrix trim dialog box.
3 . Set output volume to 100%. If the audio is too loud or distracting, mute the
output.
4 . With program material (or pink noise) present at the input, adjust the pre-
matrix trim so that the meter level in the output volume dialog box matches
the meter level in the input gain dialog box. This maintains the audio at an
optimal level in the input signal chain.
T This is a good baseline. If, after you’ve set up your microphone input gain and mix-
point levels, output processing, and post-matrix trim levels, you find that you need
more headroom to prevent clipping at the outputs, return to the pre-matrix trim
controls and lower each trim by the same dB amount.
You may also find that further minor adjustments to the pre-matrix Trim controls
help to balance out the perceived audio levels of the different inputs.