Setting Mic/Line Input And Mix Levels; Adjusting Trim; Setting Volume Control, Amplifier Stage - Extron electronics DMP 64 User Manual

Setting Mic/Line Input and Mix Levels

In this example, the mic/line input 1 signal is sent to output 1. Double-click the mix-point
( c ) for mic/line 1 – Output 1 to open the dialog for that mix-point. Unmute the mix-point
to place that signal into the mix. The default level is 0 dB, or unity gain.
Open the Input 1 gain ( a ) dialog. With a microphone attached to input #1 and gain set
to 0 dB (turn on phantom power if the mic requires it), unmute the channel. While testing
the mic, raise the fader level until the mic is clearly audible. The amount of gain and the
meter level reading will vary at this point, but as a general guideline the input gain level
should be at approximately 40 to 50 dB, and the meter averaging somewhere around
-20 dBFS. Ideally, audio should be optimized here, but voice levels at microphone inputs
can vary greatly. Having the meters average around -20 dBFS allows enough headroom to
accommodate sudden changes to voice levels. Further adjustment may be necessary.

Adjusting Trim

This is where setting gain structure becomes a balancing act. The following sections
provide guidelines, but it may take a bit of going back and forth to correctly set levels for
the installation. For example, output level can be controlled and kept below clipping using
a compressor or limiter in the output dynamics block. However, adjusting the post-matrix
trim will affect how the compressor or limiter works.
Open the output volume ( e ) and post-matrix trim ( d ) dialog. Set output volume to 100%
(mute if necessary). With program material (or pink noise) present at the input, adjust
the post-matrix trim until the meter level in the output volume dialog is below clipping (or
ideally, matches the level at the input gain meter). This maintains the audio at an optimal
level in the output signal chain while preventing clipping at the output.
Setting Volume Control for the Amplifier Stage
The maximum output of the DMP 64 is +21 dBu. As an example, assume the maximum
input level of a power amp is +4 dBu when the input attenuator is fully open. If using
the output Volume control ( e ) of the DMP 64 to control volume levels to ensure clipping
does not occur at the amplifier, turn down the input attenuator of the power amp
the equivalent of 18 dB (22 - 4 = 18). That puts the amplifiers input level at -14 dB
(+4 – 18 = -14). If the amplifier setting (when the output volume controls of the DMP 64
are at maximum) is too loud for the room, it may need to be reduced further. If it is not
loud enough for the room, a more powerful amplifier may be required.
It is recommended to use the output volume or post-mixer trim control on the DMP 64 for
controlling output volume. If using loudness processing on the unit, it will only work in
conjunction with these controls.
If using the power amplifier input attenuation to control volume (using the same
power amp maximum input level) set the output volume or post-mixer trim control of
the DMP 64 to -18 dB. This is another way that clip points of the two devices will be
matched. Verify the amplifier is not clipping by observing the amplifier clip indicator.
NOTE: Using the amplifier input attenuation to control volume compromises the
signal-to-noise ratio of the DMP 64, and is not recommended.
DMP 64 • Software Control 123