Extron Electronics DMP 64 User Guide - Manual (Page 96)

Adjusting Pre-mixer Gain
After setting input gain, add desired processors into the input signal chain (see figure 58
on page 88). The pre-mixer gain control (b) 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.
2. Connect program material (or pink noise) at the input.
3. Set the output volume to 100% (mute if necessary).
4. Adjust the pre-mixer gain (b) so the meter level on the input gain dialog matches the
meter level of the output volume dialog. This maintains the audio at an optimal level in
the input signal chain.
This sets a good starting point. After setting up the microphone 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 (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.
When 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 meter level in the output volume dialog box 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 allows clipping to be overcome by lowering
the output volume (e) setting. However, 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 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 also contribute to clipping at the outputs,
and can need lowered to maintain the balance between program material (line outputs)
and voice.
DMP 64 • Software Control 90