Yamaha Graphic Equaliser Q2031B - Manual (Page 9)

ACOUSTIC CONTROL
The diagrams show the connection method for the Q2031B. The GQ2015A is connected in the same way. In case
of the GQ1031C you will need two units for a two-channel setup.
Maintaining Ideai Indoor Propagation Characteristics
Speaker systems that demonstrate flat responses in anechoic
rooms may have irregular responses in a concert hall due to
acoustic conditions. The Q2031B equalizer can be used to
minimize these irregularities.
For smoothing of the playback system response a pink noise
generator and a spectrum analyzer are needed. Connect the
noise is radiated from the speaker. While measuring the pink
noise at strategic listening positions in the room using the
spectrum analyzer, adjust the Q2031B until the preferred
response is obtained.
POWER AMP SPEAKER
- O M
SPECTRUM
ANALYZER
Ensuring Adequate Feedback Margins in Stage Monitor Systems
NOTE Depending on the room characteristics feedback can result
in howling or ringing being generated at specific frequen­
cies. In such cases the equalizer can be used to reduce lev­
els at the affected frequencies and thereby to control the
feedback, but a pink noise generator and a spectrum ana­
lyzer are again required.
Set the equipment up just as for an actual performance, and
connect the pink noise generator to a spare input connector
of the mixing console and the spectrum analyzer to a spare
output connector. After ensuring that pink noise is being prop­
erly radiated from all PA speakers and monitor speakers,
gradually raise the output level until it is evident at which
frequencies feedback will occur. Use the Q2031B to reduce
the levels of these specific frequencies.
Proper adjustment will provide a safety margin against feed­
back when the output level is raised.
Measuring instruments can only provide basic sound
realism. After you have completed the indoor propaga­
tion and feedback compensation adjustments, make the
final adjustments using the ultimate judge, vour trained
ears.
A Pink Noise Generator
generates a uniform level of random noise throughout
the audio spectrum. (Equal Energy per octave)
A Spectrum Analyzer
divides the audio spectrum into ranges and indicates
the sound pressure for each range.
POWER AMP SPEAKER
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