Setup For Feedback Control - Shure DFR11EQ User Manual

Setup for Feedback Control

The DFR11EQ will operate stand-alone as a feedback reducer. However, when
connected to a personal computer running the supplied DFR11EQ software, additional
options are available. See Computer Interface for details.
There are two basic ways in which to set-up the DFR11EQ: The "Ring Out" method and
the "Insurance Policy" method. Both are valid for different situations. The "Ring Out" method
is a preemptive measure in which the system gain is raised beyond the normal setting to
deliberately make the system feed back. The DFR11EQ will then set its filters, and the
system gain is then reduced slightly, and the system is stable and useable. This set-up
method is primarily used for systems which are operated near the feedback point and need
an extra margin of stability.
For the "Insurance Policy" method, the DFR11EQ is simply installed in the sound
system, but filters are not set prior to use. The DFR11EQ adds extra insurance against
feedback: the system is not expected to feed back, but if it does, the DFR11EQ is there to
catch it.
gain-before-feedback, but need protection from the occasional stray feedback which can
occur due to non-stationary microphones or user-adjustable gain controls.
Setup
1. Connect the DFR11EQ in the desired signal path location. See Connecting the Unit
In a Sound System.
2. Set the input and output level DIP switches to the appropriate settings for the
sensitivities of the connected equipment.
WARNING: Other equipment may potentially be damaged after DFR11EQ power
off if the DFR11EQ input is set to +4 and the output is set to –10. If the DFR11EQ
input is set to +4 and the output is set to –10, then the DFR11EQ is acting as an
attenuator, lowering the signal to the proper level for the power amplifier. If the
DFR11EQ is turned off, this attenuation is bypassed and the power amplifier will
receive too strong a signal. It is recommended that you avoid using this setting.
3. Set the system gain to minimum, and power up all of the equipment.
4. Slowly raise the gain of the system, and set the gain of each microphone to achieve
the desired level.
5. The red CLIP LED should illuminate only on the highest signal peaks. If it illuminates
more frequently, check to see that the input level switch is set properly. If it is, lower
the level of the signal coming into the DFR11EQ.
6. At this point it is highly recommended to equalize the sound system with the
DFR11EQ's built–in graphic equalizer (see Computer Interface ) or an external
equalizer. The DFR11EQ's feedback reducer is more effective on a well–equalized
sound system.
Ringing Out the System ("Ring Out" method only)
1. If necessary, clear any notch filters in the DFR11EQ by pressing the CLEAR button.
Turn off the BYPASS and LOCK LEDs if they are not already off.
2. Slowly raise the gain of the signal going through the DFR11EQ. When feedback
occurs, the DFR11EQ will insert a filter deep enough to stop the system from feeding
back.
3. Repeat step 2 until all fixed filters are set. (There are 5 fixed filters, unless changed
by the user via the computer interface.)
4. Lower the gain by 3 to 6 dB to stabilize the sound system.
Power Down
When power is removed from the DFR11EQ, all settings (graphic equalizer, feedback
filters, button states) are automatically saved to the DFR11EQ's internal non-volatile
memory. On power up, all settings are recalled automatically.
This set-up method is used for systems which already have sufficient
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