Applications
Feedback Prevention
When the overall gain of a sound system is increased, feedback will occur at frequencies where the system response has peaks. Suppose the system has an uneven frequency response like that shown in the following diagram. The frequency at which feedback will occur when gain is increased is about 500Hz. In this case, feedback may be
Room Equalization
In a sound reinforcement system for a room, the clarity of sound can be adversely affected by the room frequency response including standing waves (room resonances), reflections of sound, and relations between direct and indirect sound.
Sound Pressure Level
prevented by attenuating levels at 500Hz by 3dB to 5dB with the E131. If the overall gain is again gradually increased, feedback will occur next at about 125Hz. It may be stopped by attenuating the levels 2dB to 3dB at that frequency. In this procedure, sufficient gain in the sound system is obtained before feedback.
The E 131 is an effective tool to equalize the room frequency response to a flat response and improve sound clarity.
For example, suppose that there is a room frequency response as shown below.
Frequency
The equalizer sliders are set as shown below.
The overall response after equalization will then be as follows.
| Frequency response | Frequency response |
Before equalization | of equalizer | after equalization |
Sound Pressure Level
Frequency
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