Specifications

10
Setup for Feedback Control
The DFR11EQ hardware is designed to work in conjunction with the supplied software and a
personal computer to offer a wide range of digital sound processing options, including feedback
reduction, equalization, delay and limiting. However, the DFR11EQ may be used very effectively as a
stand-alone feedback reducer without the benefit of the software or a computer.
There are two basic ways in which to set-up the DFR11EQ as a stand alone feedback reducer:
the “Ring Out” method and the “Insurance Policy” method. Each is 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 the proper
filters. 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. This method is used for
systems which already have sufficient gain-before-feedback, but need protection from occasional
feedback occurrences due to non-stationary microphones or user-adjustable gain controls.
Setup
1. Connect the DFR11EQ in the desired signal path location. See Audio Connections.
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 the DFR11EQ is
powered down if the DFR11EQ input is set to +4 and the output is set to –10. 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 going into the DFR11EQ.
6. At this point it is highly recommended to equalize the sound system with the DFR11EQ’s
built–in equalizer (see Equalizer ) 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 and holding 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 feedback.
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.
To store filter settings in the HOLD memory
1. Set the Hold/Update DIP switch to the Update position.
2. Ring out the room until all fixed filters are set.
3. Set the Hold/Update DIP switch to the Hold position.
4. During the performance, the DFR11EQ will change dynamic filters and deepen fixed
ones.
5. After the performance, turn the power off and back on; the DFR filters are restored to the
state they were in before the performance.
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