Equalizers are Useful Tools, but Not
Stereo Panaceas
Years ago, when I tended to judge a piece of audio
equipment by the number of controls it had, I encountered my first equalizer and it was
love at first sight. All those neatly spaced knobs were a twiddler's dream, and I soon
learned that I could alter my system's sound in ways I had never imagined. Unfortunately,
almost all of the things I did made it worse.
There's no question that an equalizer can be a very useful
tool in fine-tuning an audio system, but it's a very specialized device, and many people
buy equalizers expecting them to cure all sorts of evils that they are not designed to
handle. When it doesn't work out, the users are disappointed and tend to ditch the
equipment rather than learn how to use it properly.
An equalizer is a selective level control, each part of
which affects only a portion of the audio range. The simplest are ordinary tone controls
which are basically two-band equalizers that divide the audio band into an upper and a
lower section and gives you control of each.
Generally, the more bands there are, the finer the control
that can be exercised, but increasing the number of controls tends to make the equalizer
both more difficult to use and more expensive. Freestanding units usually provide at least
seven bands; for home use, the most common is the "octave equalizer," which
controls 10 bands, each roughly an octave wide.
Very early equalizers, like the one I first played with,
used a panel full of rotary controls, but this made it difficult to know exactly what you
were doing. Now, almost all equalizers use linear controls, neatly lined up beside one
another. The ability to see the equalizer settings as a curve has resulted in this sort of
device being known as a "graphic equalizer."
New equalizer owners often find uncontrollable the urge to
"correct" absolutely everything, and this should be discouraged. But there are
times when the sound can definitely benefit from a little judicious tweaking. Recordings
often suffer from the heavy hand of an engineer playing with his own equalizer, and a home
or car unit can be just the ticket to undo such sonic abuse.
Older or damaged recordings might also benefit from some
equalizer massaging. This may in fact reduce their fidelity somewhat in absolute terms,
but it might also make them listenable. Damaged LPs, for instance, can often be rendered
tolerable by reducing the top couple of bands, where most of the surface noise and
distortion occurs. Any dulling of the sound can be offset to some degree by giving a bit
of boost to the part of the spectrum just below the attenuated bands.
Where audio enthusiasts usually harbor the most expectation
of an equalizer -- and where they most often get into trouble -- is as a remedy for
equipment or acoustic ailments. There seems to be a popular belief, for instance, that if
your speakers are lacking in bass, you only need add an equalizer to pump up the level.
But if there is a major deficiency in bass, correcting it by equalization means fighting
the speaker's inherent limitations, and pumping more watts to the speaker is likely to
cause high levels of distortion. The same is true at high frequencies, although the
effects may not be as severe.
Equalizers tend to fare better when they are called on to
reduce rather than boost levels in certain parts of the band, so they work quite well for
taming tubby lows or strident highs. In any case, the watchword should be moderation --
almost anything you can do with an equalizer will sound better if you do less of it. And
don't be fooled by ads or promotional pictures in which the sliders trace out the peaks of
the Rockies; if a system needs that much equalization it should be junked.
The principle of moderation is particularly true when it
comes to the correction of the sonic glitches that inevitably happen in real acoustic
environments. Equalizers can indeed work wonders in some circumstances, but the effects of
a room on sound traveling through it are different for every speaker and listener
position, so even perfect equalization can only be achieved for one spot; even moving your
head a few inches either way will destroy the effect.
Used properly, equalizers have a well-earned place in
audio. Misused, as they frequently are, they can be an expensive way to achieve poorer
sound. It is worth taking the trouble to use such a valuable tool correctly.
...Ian G. Masters
ian@mastersonaudio.com
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