EQ (part 3)
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 doesnt 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 isnt 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. Its 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. Its something that will come automatically after a time, but newcomers to recording often concentrate more on the change in the sound itself and dont notice that it has suddenly become more or less prominent in the mix.
Enough of the technical stuff, recording is an artistic occupation so lets consider the subjective facets of EQ. If we consider individual sounds first, lets 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 oclock 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 instruments 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 instruments 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 dont 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 dont consider to be any use to the instrument, freeing up a space in the frequency spectrum for another instrument to use.