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This equalizer is designed to provide room equalization, feedback control, and system tone control. No
amount of equalization will correct an acoustically bad room/mic/speaker arrangement or completely correct
the response curve of a poor loudspeaker.
Always begin with all sliders in the “0” position and avoid excessively cutting large segments of the audio
passband, as this will limit the system's dynamic range.
Exercise caution when attempting to boost equalization below cutoff of the speaker system. Typical sound
reinforcement enclosures are not designed for 20 Hz performance and transducer damage could result.
LOW CUT (1)
Provides high pass filtering at 40 Hz in the “in” position. Low frequency roll-off is at 12 dB per octave. There
is one on each channel.
LOW CUT LED (2)
With the low cut switch in the “in” position, this LED will illuminate indicating a low frequency roll-off at 12 dB
per octave at 40 Hz. There is one on each channel.
BYPASS (3)
In bypass mode (switch in), the input signal is routed directly to the output and is unaffected by all front
panel controls with the exception of the low cut filter. There is one on each channel.
BYPASS LED (4)
This LED will illuminate when the bypass switch is in the “in” position indicating that the EQ and gain
controls are bypassed. There is one on each channel.
EQUALIZER SECTION (5)
31-bands of 1/3 octave filters. The filters are constant “Q” devices located at ISO center frequencies. Effec-
tive equalization range is from 20 Hz to 20 kHz. Maximum boost per frequency is 12 dB and the maximum
cut per frequency is 18 dB.
AUTOMATIC FEEDBACK LOCATING LEDS (6)
When feedback occurs, the LED of the frequency band that is feeding back will illuminate over the slider that
needs adjusting. The LED will remain illuminated for a few seconds even after the feedback is gone. This
allows you to see where the feedback is if the feedback goes away before any correction is made. If there is
no feedback occurring, all the LEDs will become active acting as a basic real-time analyzer.
OPERATING THE FEEDBACK LOCATING SYSTEM
The feedback locating system is normally used in one of two ways.
1. To catch and reduce/eliminate feedback “on-the-fly” during a performance.
2. To determine frequency bands that are susceptible to feedback before the performance, and elimi-
nate them in advance. This is done, after the system is set up, by bringing up the microphone levels
slowly to the point of feedback. As they start to feedback, note the LED activity on the Q231 FX.
Move the faders to decrease the “identified” bands. Now you have eliminated a high percentage of
potential feedback problems before the performance even begins.
Note: It is not uncommon for feedback to occur over several frequency bands. Also, go easy when making
fader adjustments since extreme movements will affect your performance and be counter productive. Some
feedback or ringing, although audible, may not be louder than the other program material and may not light
an LED.
GAIN (7)
Calibrated control for regulating overall gain of the equalizer section. Unity gain throughout the signal chain
may be maintained by recovering lost signal at this point.
For example: Assume the equalization process has introduced a signal loss of -6 dB by negative ( - )
adjustment of the EQ section. The gain should then be adjusted to +6 dB to maintain unity gain through the
equalizer.
