Successful EQ requires good equipment and a thoughtful approach from the engineer.
Experienced engineers EQ by instinct and their fingers operate the controls
as fluently as a jazz pianist plays the keyboard. But this fluency doesn’t
come automatically, it can only be won by experience. Anyone can grab the low
frequency control and wind up the bass to the maximum, but if you are serious
about your recording then you will realise that it isn’t just yourself
you have to please, you have to consider what other listeners like, and what
systems they may be playing the recording on. There is also a good technical
reason why you should think before adding a lot of bass: for a given level of
input, any small or medium size loudspeaker will produce much more sound at
mid frequencies than at low, and if you boost the low frequencies too much then
the overall level the speaker can achieve without significant distortion is
less – sometimes much less. It’s a matter of compromise: the more bass
you add, the lower the overall level can be. This applies to other frequencies
too in the mixing console itself. Adding EQ adds level, and it is very easy
to boost the signal so much in the EQ section of the console that you run into
clipping and distortion. Since the fader comes after the EQ, lowering the fader
will do nothing the solve this. The answer is to reduce the gain to allow the
signal a little more headroom if necessary. One further technical point: changing
the EQ of a signal nearly always changes the level, so each time you change
the EQ you will have to consider moving the fader to compensate. It’s something
that will come automatically after a time, but newcomers to recording often
concentrate more on the change in the sound itself and don’t notice that
it has suddenly become more or less prominent in the mix.
Enough of the technical stuff, recording is an artistic occupation so let’s
consider the subjective facets of EQ. If we consider individual sounds first,
let’s assume that the signal coming from the microphone is already as perfect
as can be, as the result of careful positioning and angling. Each instrument
has certain bands of frequencies that are strong and some that are weaker. The
human voice for example is very strong at around the 3 to 4kHz region, no matter
whether male or female, or what note is being sung. When using EQ, you will
be considering which characteristics of the sound you want to accentuate, or
which you want to reduce. One way to consider this might be to imagine an instrument
which was an ‘average’ of all real instruments, where the characteristics
of normal instruments were smoothed out into something that had a neutral sound.
When EQing a real instrument, you will either want to exaggerate its individual
characteristics and make it more distinctive, or reduce its individuality and
make it more like this hypothetical ‘average’ instrument. This is
quite simple to do, and we can make use of the standard sweep mid range control
that is found on most mixing consoles, with controls for frequency and gain.
A fully parametric equaliser with a Q control can offer even more precision.
First set the gain control to a medium amount of boost – the 3 o’clock
position of the knob is usually OK. Now sweep the frequency control up and down
to the limits of its range and listen for the frequencies at which the effect
is strongest. These are the frequencies in which the instrument is rich. Boosting
the instrument’s strong frequencies will enhance its individual characteristics
and, for example, make a clarinet even more dissimilar to an oboe or any other
instrument. You are making the clarinet even more clarinet-like. When you have
found the instrument’s strongest frequency band, set the amount of boost
according to taste, and always compare what you are doing with the flat setting.
If you have EQ sections to spare, you may be able to cut down on frequencies
which don’t enhance the sound of the instrument. Some instruments which
are not known as bass instruments nevertheless have a high low frequency content,
cymbals for instance. On many occasions it will be well worth cutting down on
frequencies which you don’t consider to be any use to the instrument, freeing
up a space in the frequency spectrum for another instrument to use.