SESSION NOTES 15 “Mastering” (part 5 “Using EQ”)
Hello to all those still alive. This month I want to look at the various uses of EQ used in mastering. Mastering essentially is the art of getting the optimum sound out of a stereo track. EQ in my opinion is the most important tool because you are shaping the tone of the music across the entire audible spectrum. Typically this range is from 20Hz at the bottom end up to 20Khz in the top end. The difference in sonic quality between tracks destined for an album can be huge, even when the tracks are recorded in the same studio by the same engineer with the same band playing the same instruments!!
Often these days artists are more likely to release single tracks one at a time on-line using streaming or download platforms. The pressure to have a consistent sound across an album simply doesn’t exist with this scenario.
So, where do we begin. It’s the first impression that is the most important when i’m playing a track for the first time. is it too bright, is it muddy, can you hear all the detail present in the mix, does the bass dominate the whole mix etc. One of the most common requests i get is to do with vocal levels. In a song, the vocal is ‘GOD’. There is no other element that is more important, period. When mastering you can raise or lower the vocal level in a mix by ‘zoning in’ on the fundamental pitch. You need to have a very narrow bandwidth (or ‘Q’ factor) and to know what key the song is in. It is then a matter of raising or lowering the gain of the EQ to sit the vocal more comfortably in the mix. This practice is quite tricky to get right and really i should be sending the band away to get a new mix with the vocal levels adjusted to suit the track. This unfortunately is not always possible so it will be up to the mastering engineer to save the day.
Now the key of the song is vital when it comes to choosing the frequencies to work on. EQ’ing a track in the key of ‘A’ for example means i’ll be using 55Hz (or multiples thereof) in the case of the bass elements of a mix. Each octave is a doubling of the frequency so in the key of ‘A’ it will be 55Hz, 110Hz, 220Hz and so on all the way up to the top. This is a very powerful technique when EQ’ing music and it’s something i discovered myself over 30 years ago. You can of course use this technique whilst recording and mixing too. Here is a link to a very useful frequency chart. https://www.audio-issues.com/music-mixing/all-the-eq-information-youll-ever-need/ This is a pretty comprehensive site to get you started.
Balancing the tone of a track is a little more complicated due to the inherent nature of different genres of music. Hip-Hop and Rap tracks for example rely on excessive bass frequencies as opposed to folk music which tends to focus on the midrange. EQ can be split into different ranges thus. Sub bass, bass, lower mid, mid, upper mid and treble. Now the two extremes of this range are best dealt with by using ‘shelving’ EQ’s. These can be quite gentle but extremely effective in adding general ‘weight’ to a mix down in the bottom end and ‘air’ up at the top end. Conversely i also use an HPF (high pass filter) to remove super low frequencies below 20Hz. These super low frequencies are essentially redundant because speakers don’t reproduce them and they eat up a lot of headroom. Once you’ve filtered them out you can work on the audible part of that spectrum much more accurately and with much better results. The same happens up at the top end when you have way too much high frequency content that makes the sound very brittle. Use a LPF (low pass filter) to tame these high frequencies rather than a peak EQ for a much smoother result.
So, remember it is very useful to know the key of the track so you can get straight in on those problem frequencies rather than randomly EQ’ing in the hope that you might chance upon the solution.
Next month i shall continue the EQ journey looking at sonic problem fixes.