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
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 (
(figure
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 (
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 (
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 (
E
any position where clipping occurs), it is best to adjust the pre-mixer gain (
trim ( ) control to prevent any possible clipping.
D
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.
figure 69 on page 102,
), output volume (
A
69).
) so the meter level of the input gain matches the meter level of
B
). Unless a user is prevented from changing the volume setting to 100% (or to
) is used to compensate for level changes
B
), and pre-mixer gain (
E
) and lower each one by specific amounts.
B
DMP 128 • Software Control
) dialog boxes
B
) or post-mixer
B
104