TOA Electronics 1000 Series - Manual (Page 7)

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 prevented by attenuating
levels at 500Hz by 3dB to 5dB with the E-1231. 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.
Sound
Pressure
Level
Frequency
Room Equalization
In a sound reinfocement 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.
The E-1231 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.
The equalizer sliders are set as shown below.
The overall response after equalization
will then be as follows.
Sound
Pressure
Level
Frequency
The equalizer sliders are set as shown below.
The overall response after equalization will then be as follows.
Sound
Pressure
Level
Frequency
Before equalization
Frequency response
of equalizer
Frequency response
after equalization
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