Equalisation  (equalization, or 'EQ' for short) is undoubtedly one of the most commonly used types of audio processing in music production and its application can range from subtle enhancement / correction to extreme tonal reshaping. In this production tip we're going to take an introductory look at how to get started using EQ.

 

If you've ever fiddled with the bass and treble controls on your hi-fi then you've used an EQ. The studio version of this works on much the same basis but with a lot more flexibility in terms of tuning the processor to get precisely the desired effect.  Equalisers come in both hardware and software forms and tend to be pretty similar in terms of the controls on offer, so lets take a look at what these are:

This has been a quick introduction to some EQ basics, we hope you found it useful and we'll be back with a more advanced follow-up in the near future.  

 

 

 

 

 

 

 

 

Finding just the right frequency to cut or boost is key to getting the best out of EQ. A good technique is to use a Peaking EQ with a high Q setting (i.e. narrow band) and dial in quite a lot of boost, say 6dB+. If you then sweep this EQ up and down the frequency range while your audio is playing back you should hear particular aspects of the sound being brought out. This is particularly effective for identifying areas to cut such as ringing frequencies. By sweeping up and down you should be able to focus in on the centre frequency of the ringing and then cut a few dB there (again using a Peaking EQ, set to a fairly high Q setting). Although most Equalisation is applied by ear, it's still a good to have some idea about how frequency ranges translate into everyday descriptions to give a clue to where to start looking. Here's a rough guide . . .

 

 

Which EQ Type?

We covered high and low pass filtering in a previous production tip. Essentially they are great tools for getting rid of unwanted frequencies which don't contribute to the core of the sound, such as low rumble. In general a Peaking EQ is good for focusing in on a particular frequency range that you want to cut or boost, maybe injecting some extra warmth or attenuating ringing. Shelving EQs because they continue to boost above or below the centre frequency should be used when you want to affect a wide frequency range, maybe dipping the entire bass slightly or opening out the top.

 

In general it's best not to commit to EQ settings at the recording stage, or if you do, to keep them pretty subtle. It could be worth switching in a high-pass filter, but again there is plenty of scope to apply this at the mixing stage. There isn't a prescribed approach to EQing a mix, but one possible option is do a first pass across all your channels doing any filtering and corrective work and then come back, perhaps after looking at other aspects of the mix, to consider enhancement. This is pretty much how we approach EQ in the mastering studio. We tend to apply equalisation in two stages, first using a very precise digital EQ for transparent corrections and following this with an analogue valve-based EQ for some characterfull enhancement.  

 

However you work it's important to remember that an Equaliser is a very powerful tool capable of completely destroying you recording if used incorrectly. If you are unsure about the accuracy of your monitoring environment then it's best to EQ conservatively. Also, if you find yourself having to use quite radical EQ settings then it might be worth considering re-thinking the original sound used.

We don't always want equalising to produce 'natural' sounding results, and a good example of EQ as an effect is 'lo-fi': For this you need both high and low pass filters, set to somewhere around 1 and 4 kHz respectively. And then dial in slight presence peak a around 3K. Combined with some heavy compression or a guitar amp simulator, this cutting-off of the bass and treble gives you that classic lo-fi telephone effect.