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MICROPHONE PREAMPLIFIER
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Instruction Manual
6. TYPICAL OPERATION
Changing the polarity of one or more mics will often clear up the problem. It is always
worth the time to experiment with mic polarity.
6.6 GROUPING CHANNELS
It is possible to create a group of channels, and treat them all together with any or all of
the preamp control functions.
Grouping Caveats
Several properties of group operation are important to know as they may affect the way
you use grouping.
1. The Model 1788A computes the modified individual channel gains in an invisible
workspace that can retain over- and under-range values. This allows the unit to be
able to restore the channels’ gain relationships if you reverse the direction of group
gain shift after one or more channels have limited out. However, the workspace
memory is erased when exiting the MULTIPLE SELECT mode, and all channel gains
become normalized with their new ratios or differences.
2. The individual channel functions will remain unchanged within the group until a
function is operated. At that time, whatever function is operated passes to all in the
group and the function will not revert to the original values upon leaving MULTIPLE
SELECT mode.
Creating a Group
To create a group, first go into LOCAL control. Then press the MULTIPLE SELECT button.
Now individually press the buttons for the channels you want to group. The grouped
channel buttons will all be lit. To remove a channel, press its button again.
Disengaging the Group
Press the MULTIPLE SELECT button again and the group will disappear.
NOTE:
Once a group has been created, it’s definition stays in memory. Next time you press
the MULTIPLE SELECT button, the previous group will appear. You can change the
group simply by pressing the channel buttons to remove or add channels.
30
35
45
55
50
55
65
65
85
30
35
45
55
Ramp Up
Group 20dB
Ramp Group
Back Down 20dB
Internal Over
Range Memory
Internal Under
Range Memory
Upper Limit
Lower Limit
HOW GROUP GAIN CONTROL WORKS
