How to use MID/SIDE EQ

Today we look at Mid Side EQ. 

Most mixes are bounced out in stereo, where we have some instruments placed in the centre of the stereo field, where they are equal on both speakers, or we pan other instruments so they sound more to the left or right at varying degrees. We also tend to widen some of the sounds by using reverb or delays or even specialized widening plugins, so that material is spread to the edges of the mix.  

Generally speaking in a mix, the lead vocals, bass, kick and snare tend to be centred, with pads, synths, backing vocals and guitars panned to the left or right and wider out in the stereo field, and then of course, the effects are also spread to the edges for width in the mix. Ok, that all said, let’s have a look now at the EQs. 

Mid-side equalization is versatile and effective. You can use it for corrective mixing work, mastering, sound design, creative effects, and more. It’s really up to you! And your ears. Remember that working with any EQ requires a lot of analytical and critical listening. You can easily mess up the tonal balance of a mix, so as always start cautiously until you are more confident in your technique. And use reference tracks. Find your favourite production in the genre you are mixing and listen to what they are doing. Compare your tracks and you will learn so much as you build your skill set. 

Before you get working on those frequency adjustments, it’s important to know the difference between the normal chnnel EQ and Linear Phase EQ. 

In Logic Pro X for example, The Channel EQ is called minimum phase EQ, where the different bands in the Audio Spectrum crossover (where the frequencies overlap) and cause some minor phase interactions that can colour the sound at the crossover points. 

This is great in some instances on individual channels, to help you add that little ‘something’ to spice up your sound. In mastering though, you generally are wanting something that is more transparent. So a linear phase EQ is a smart choice. 

In Logic Pro X, The Linear Phase EQ keeps the phase between the bands linear, meaning that the EQ compensates for those timing and phase issues at the crossover frequencies. So there is no colouration of the signal. They use quite a bit of CPU power, so they are really useful for Master or Buss processing. They’re not really useful stacked on loads of different channels.  

Effective Mid-side EQ processing will give your mix more presence, clarity, and balance at the mix and mastering stages.  

Here are some classic techniques when using MS EQ: 

Widen the stereo image to create a nice full sound 

A big stereo image is often really useful in sound design, but it can also create a wonderful listening experience for your audience. Using Mid Side EQ, you can create a wider stereo image on either the full mix or individual elements.  By adjusting the balance between the mid and side levels of the EQ, you create that width. Boosting high frequencies in the side channel or attenuating low frequencies in the mid channel, will give you that width. 

A quick way to achieve width is to use a high shelving filter and boost around 8KHZ, or higher, in the side channel. As always, listen, and adjust the frequency and level to suit your material. 

Tighten up the low end  

To keep your bass tighter, present and focussed as well as give you a little more headroom in your mix, you want to look at keeping low-end sounds like the kick and bass centred  in a mix.  Ensure that the lowest frequencies in your mix are mono, and reduce/ remove low frequencies from the sides, as these could cause clarity and phase issues. Most modern basslines in electronic music typically have the low end content right down the middle nice and centred, with a nice splash of wider harmonic frequencies in the high-end.  

If you are dealing with a stereo bassline, then EQ the bassline to preserve a nice tight punchy mono signal, while still keeping the higher harmonic content.  You  can create this separation by cutting low frequencies from the side channel. A useful tool here will be a spectrum analyser in conjunction with your ears. Where you cut will depend on your content. But, a good place to start is to use a nice shelving filter and cut between 75 and 300Hz. Just be careful not to cut too much from the sides, or you will land up with a thin weak sounding bass. Just use your ears!  

A nice boost in the basslines mid channel using a bell filter at around 170Hz might give the bass signal a nice bit of presence in the mix. Experiment with the Q setting to really craft the sound you need. 

Reduce the mud in the mix and get your lead vocal to stand out and be present 

The lead vocal is usually centred in the mix, so try  boosting the mid-range frequencies on the mid channel and attenuating low frequencies on the sides. Use a low shelf in the sides to cut from 200Hz or lower.  This move keeps the mid-range focused in the centre and pushes the high-end information to the sides. 

Tonal Balance for Mastering 

The goal of mastering is to have a song that sounds pleasing and cohesive, a mix that translates well on various playback systems. The overall tonal balance of a song is all about each elements sonic contribution. When you have a tools such as MS EQ, you are able to address and correct tonal imbalances. You can balance the tonal spectrum by boosting or attenuating different areas of the mix.   

One of the best ways to achieve tonal balance using MS EQ is to use a broad bell filter on the mid channel and make subtle level changes.  Try also cutting the really low rumble in the mid channel at around 30hz and below, using a low cut filter, and then add that ‘sheen’ on the side channel with a boost in the high frequency area around 7-14KHz, using a shelving filter to add the brightness, width and presence you want in the mix.  

As always, watch that spectrum analyser and listen, you want to try to achieve perceived equal loudness across the frequency spectrum. And ensure that you are not disrupting the cohesiveness of the mix. Small changes often make a huge difference. Just be careful, and listen, but really, a whole new dimension of mixing and mastering awaits! 

We asked Bronwen from www.rapponline.net to walk us through using Mid-Side Eq on the Master Buss of a mix. 

Keep Experimenting! 

The r-loops team!