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The next thing you can do with equalizers is to improve the way
each venue sounds. Every room sounds different fact of life —
fact of physics. Using exactly the same equipment, playing exactly
the same music in exactly the same way, different rooms sound different
guaranteed. Each enclosed space treats your sound differently.
Reflected sound causes the problems. What the audience hears is
made up of the direct sound (what comes straight out of
the loudspeaker directly to the listener) and reflected
sound (it bounces off everything before getting to the
listener). And if the room is big enough, then reverberation
comes into play, which is all the reflected sound that has traveled
so far, and for such a (relatively) long time that it arrives and
rearrives at the listener delayed enough to sound like
a second and third source, or even an echo if the room
is really big.
It’s basically a geometry problem. Each room differs in its
dimensions; not only in its basic length-by-width size, but in its
ceiling height, the distance from you and your equipment to the
audience, what’s hung (or not hung), on the walls, how many
windows and doors there are, and where.
Every detail about the space affects your sound. And regretfully,
there is very little you can do about any of it. Most of the factors
affecting your sound you cannot change. You certainly can’t
change the dimensions, or alter the window and door locations.
But there are a few things you can do, and equalization is one of
them. But before you equalize you want to optimize how
and where you place your speakers. This is probably the
number one item to attend to. Keep your loudspeakers out of corners
whenever possible. Remove all restrictions between your speakers
and your audience, including banners, stage equipment, and performers.
What you want is for most of the sound your audience hears to come
directly from the speakers. You want to minimize all reflected sound.
If you have done a good job in selecting and equalizing your loudspeakers,
then you already know your direct sound is good.
So what’s left is to minimize the reflected sound. Next use
equalization to help with some of the room’s more troublesome
features. If the room is exceptionally bright you can beef up the
low end to help offset it, or roll-off some of the highs. Or if
the room tends to be boomy, you can tonedown the low end to reduce
the resonance. Another way EQ is quite effective is in controlling
troublesome feedback tones.
Feedback is that terrible squeal or scream sound systems get when
the audio from the loudspeaker gets picked-up by one of the stage
microphones, re-amplified and pumped out the speaker, only to be
picked-up again by the microphone, and re-amplified, and so on.
Most often, this happens when the system is playing loud. Which
makes sense, because for softer sounds, the signal either isn’t
big enough to make it to the microphone, or if it does, it is too
small to build-up. The problem is one of an out-of-control, closed-loop,
positivefeedback system building up until something breaks, or the
audience leaves.
Use your equalizer to cut those frequencies that want to howl; you
not only stop the squeal, but you allow the system to play louder.
The technical phrase for this is maximizing system gain before
feedback.
It’s important to understand at the beginning that you cannot
fix room related sound problems with equalization, but
you can move the trouble spots around. You can rearrange
things sonically, which helps tame excesses. You win by
making it sound better. Equalization helps.
Equalizers are useful in augmenting your instrument or voice. With
practice you will learn to use your equalizer to enhance your sound
for your best personal expression: deepen the lows, fill the middle,
or exaggerate the highs — whatever you want. Just as an equalizer
can improve the sound of a poor loudspeaker, it can improve the
sound of a marginal microphone, or enhance any musical instrument.
Equalizers give you that something extra, that edge. (We
all know where “radio voices” really come from.)
Seeing Sound
To make loudspeaker and sound system measurements easy, you need
a real-time analyzer (RTA). An RTA allows you to see the power response,
not only for the loudspeaker, but even more importantly, for the
whole system. Stand-alone RTAs use an LED or LCD matrix to display
the response.
A built-in pink noise generator (a special kind of shaped
noise containing all audible frequencies, optimized for measuring
sound systems) is used as the test signal. A measuring microphone
is included for sampling the response. The display is arranged to
show amplitude verses frequency.
Depending upon cost, the number of frequency columns varies from
10 on 1-octave centers, up to 31 on 1/3-octave centers (agreeing
with graphic equalizers). Amplitude range and precision varies with
price. With the cost of laptop computers tumbling, the latest form
of RTA involves an
accessory box and software that works with your computer.
These are particularly nice, and loaded with special memory, calculations
and multipurpose functions like also being an elaborate SPL meter.
Highly recommended if the budget allows. For a budget-effective
alternative, see Rane’s RA 27 for an easy to use, low-cost
unit.
Rane pioneered the simple RTA with the RA 27’s introduction
in 1984. Not only was the RA 27 the first, but it remains the leader
in affordable, easyto- use, precise and reliable RTAs.
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