AudioControl SA-3052A, Руководство по эксплуатации

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SA-3052A Owner’s Manual
8-2
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Chapter 8 - Applications
as a diaphragmatic absorber (the acoustical equivalent of a black hole). If that is the case,
then structural modification of the offending surface is the only real cure. If you get really
desperate, there’s always explosives.
If you’re using an octave-band equalizer, you’ve probably noticed that the ana-
lyzer has a few more bands than the equalizer does. With octave-band equalizers and
octave-band analyzers, the important thing that is missing is the response characteristic
in-between adjacent bands. The equalizer’s controls interact with each other, allowing
you to affect the response in the sidebands. If the EQ controls didn’t interact, the equal-
izer wouldn’t be very useful...let alone musical. The SA-3052A shows you what is going
on in-between the bands of the equalizer and the effects of the controls away from their
band-centers. Because of the interaction, you can still deal with problems that aren’t con-
veniently centered on a particular control by splitting the difference between two adjacent
controls.
Regardless of which equalizer you’re using, an overall guiding principle is: “Less is
Better.” With good components to start with, all that should be needed is gentle, gradual
shaping. Avoid large amounts of boost or cut as well as sharp discontinuities in the over-
all curve.
Once you’re finished, you’ll want to add a controlled amount of high-frequency roll -
off. Why? Because “ruler-flat” speakers sound unnaturally bright to most ears. Ordinarily
we hear most sounds at a distance. This causes high-frequency loss because of the friction
between the sound wave and the air, as well as other losses due to absorption caused by
walls and other surfaces. As a starting point, try 1 to 3 dB per octave, starting somewhere
between 1 and 8 kHz. Experiment; let your ears be your guide and the
SA-3052A be your compass.
Sound System Equalization
Equalizing a large sound system isn’t much different from equalizing a stereo
system. Granted, the scale of things is quite different, but the process is more or less the
same.
One thing that you need to keep in mind when equalizing a system in a large space
is that the equalized response curve represents the average response taken at many points
within the room. This alone can make the equalization process quite tricky. The aiming
of the components of the array, their mechanical alignment, and their directional charac-
teristics all contribute. It’s easy to make the system curve look right at one point, but how
about the other seats in the room?
One source of problems is picking a microphone position that is too close to the
loudspeakers. If the loudspeaker has flat power response throughout its coverage pattern,
then you are safe. If not, then what happens is that you end up equalizing the direct field
response, which is fine at that location but since the power response isn’t flat, you get a
lumpy response curve at other locations. On the other hand, if you equalize outside of
the direct field (in the reverberant field) and successfully flatten things out then the direct
field will be lumpy. The solution is constant coverage loudspeakers that maintain their
directional characteristics over a wide frequency range.