Let start to equalise. If our sound system is monoamplified, adjust the high pass filter, in
such a way that limit the bandwidth to the bandwidth that the speakers of the system can
reproduced. With this we will avoid to amplify signals which will not be reproduced and to
send signals to speakers which are not able to reproduce.
If using an spectrum analyzer, now the time has come to make the measure of the
response curve of the sound system. Remember to maker several measures and to average
them out.
Equalise till the response curve is plane, or if you do it by ear, try to get the biggest
power without loosing the intelligibility. To leave the overall response curve plane, first of all
you have to attack the big peaks, when the first one had been pulled down, find the next one
and repeat the procedure as many times as it might be necessary. When finished it, adjust
the level control to solve the gain loose.
If the peak gets on between two bands of the equaliser, then divide the difference by
both of them.
Do not try to equalise out dips in the overall response curve, unless they are quite
shallow (less than 3 dB), because the power waste used for that is very high (3 dB = 2 x
power). In any case, our audition is more sensitive to the presence of anything than to its
absence, and therefore we will hear the peaks in the response before perceiving the ab-
sence in the dips.
Once the levelling of the total curve is completed, listen to the system with music and
voice. In some cases it can be advisable a gradual attenuation in the high frequencies zone,
for instance from 1 to 3 dB per octave, starting in some point between 1 and 8 KHz.
Listen to the system for a long while, and vary the volume levels. If the total curve of the
equalization system is not right, the listening fatigue will indicate that you have not finished
yet. You have to give some more tries to leave it well.
To end, you need to known the following principle: the less equalised in the system, the
better.
7. BLOCK DIAGRAM AND HOW IT WORKS.
In the input stage, the signal is electronically unbalanced, and after that the level indi-
cator control take the first reading point of the signal level. Later the signal crosses the level
control, and in the level control output is placed the high pass filter (H.P.F.) behind it is the
second reading point of the signal level by the level indicator control.
In the model EQ-230, the signal crosses the parametric filter controls, that provide a
gain control, a frequency control and a bandwidth control, the parametric filter ON/OFF
switch controls that the signal crosses this controls or not. Following this controls its the third
reading point of the signal level by the level indicator control.
The fifteen or thirty band-pass filters (depending of the equaliser model) of the equaliser
come below, with the equalisation range selector (±12 dB or ±6 dB). Follow this it is the BY-
PASS switch that take the signal after the band-pass filters or after the level control, depend-
ing on its position (ON-OFF).
Immediately after it is the last reading point of the signal level by the level indicator
control, as well as the feedback finder system (only model EQ-230), that setup by means of
the faders state setup switch, controls the fader LEDs configuration.
Lastly the signal is electronically balanced, and crosses the turn on delay relay up to the
output connector. The turn on delay relay is controlled by the turn on delay circuit, that leave
in BY-PASS the equaliser, when this is turn off, and when it is turn on for a few seconds to
avoid the turn on transients
17
ALTAiR
EQ-215/230 GRAPHIC ECUALISERS
Содержание EQ-215
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