Adjusting Trim; Adjusting Pre-Mixer Gain; Setting Output Gain Structure - Extron electronics DMP 128 User Manual

adjusting Pre-mixer gain

After setting input gain, add desired processors into the input signal chain. The pre-mixer
gain control (see figure 63, b on page 101) is used to compensate for level changes due
to processing. Adding a compressor generally reduces the signal level, while a filter can
boost or cut the overall signal level. When changes are made to filter settings after setting
dynamics processors, re-check the levels in the dynamics processors to make certain
they are still valid.
notE: This procedure is valid only when there is no active processing in the output
signal path, and if the post-matrix trim value is set to 0 dB, unity gain. If processors
are inserted in the output signal path, engage Bypass to temporarily remove them.
To adjust pre-mixer gain:
1. Open the line input gain ( a ), output volume ( e ), and pre-mixer gain ( b ) dialog boxes
(see figure 63).
2. Connect program material (or pink noise) to the input,
3. Set the output volume to 100% (mute if necessary).
4. Adjust pre-mixer gain (see figure 63, b ) so the meter level of the input gain matches
the meter level of the output volume. This maintains the audio at an optimal level in
the input signal chain.
This sets a good starting point. After setting up the mic input gain and mix-point levels,
output processing, and trim levels, if more headroom is required to prevent clipping at
the outputs, return to the pre-mixer gain controls (see figure 63, b ) and lower each one
by specific amounts. Further minor adjustments to the pre-mixer gain controls help to
balance perceived audio levels of the different inputs.
Using the pre-mixer gain for output volume control, the procedure can be reversed. Set
pre-mixer gain to 0 dB. With program material (or pink noise) present at the input, adjust
the output volume until the output volume meter level is below clipping (or ideally, matches
the level at the input gain meter).

setting output gain structure

Add all desired processors into the output signal chain. Keep in mind that a filter can
boost or cut the overall signal level and adding a compressor generally reduces the signal
level. Inserting either or both can require resetting of the output volume.
Since a limiter is the most likely choice for output processing and can only reduce the
signal to prevent overload, a reduction of output level does not have to be considered.
Loudness boosts the overall signal level, but only at lower volume settings
After adding processors to the output signal chain, the output volume level can clip when
set to 100% (or less). Floating point DSP can overcome clipping by lowering the output
volume (see figure 63, e ). Unless a user is prevented from changing the volume setting to
100% (or to any position where clipping occurs), it is best to adjust the pre-mixer gain ( b )
or post-mixer trim ( d ) control (see figure 63) to prevent any possible clipping.
Alternately, use the post-mixer trim controls to adjust output volume. Post-mixer trim
controls provide 12 dB of gain, so use a group master with soft limits to control levels,
setting an upper limit of 0 dB or less. Mic levels can also contribute to clipping at the
outputs, and can need lowered to maintain the balance between program material (line
outputs) and voice.
DMP 128 • Software Control 103