Several EQs now have a mid/side mode. This opens up a lot of possibilities, but can be difficult to use effectively. Instead of simply tweaking the sound or the range of the controls, mid/side mode completely changes how the EQ behaves and sets new rules for how it can be useful and effective.
It helps to stop thinking about mid/side EQ as an equaliser – but instead to think of it as a surgical frequency-focussed stereo width adjuster. It works best on complex stereo material, such as groups or the mix bus.
- Mono bass. Not just bass, but lower mids too. It’s easy – use a highpass filter or low shelf (with negative gain) on the side channel. If you’ve mixed well, this won’t actually reduce the level or impact of your low frequencies (especially the ever-critical kick and bass). Instead, it will add focus and tightness in a way that doesn’t detract from the overall perceived stereo width of the mix. Experiment with the frequency – you’ll find you can probably go a lot higher than you might have expected. Unlike simply collapsing the kick and bass channels, using a mid/side EQ (particularly with a higher filter frequency) will also catch the lower mids in other instruments. And instead of making space in the mix by reducing their level, the mid/side EQ maintains their energy by simply collapsing them to mono.
- Top end dimension. This is achieved by utilising a high-end boost on the side channel. Usually only a small amount is required – less than 6dB. Doing this to a mix can add dimension and air without the harshness of other tools (such as harmonic exciters or other saturation). It can also help open up a ‘small’ mix without losing the focus in the lows and mids. Some mixes will benefit from a more balanced approach – instead of adding 6dB to the top of the side channel, try adding only 3dB to the top of the side channel as well as reducing 3dB from the top of the mid channel. Not all mixes will benefit from this – it will sound more like a regular EQ boost if the top of the mix is already quite wide.
- Focussed vocals. This can be done by reducing the width of the midrange. As with the above two tips, the most transparent way of doing this is by adjusting the side signal (by applying a dip using a parametric band) while keeping the mid signal untouched. Doing this can reduce a lot of clutter surrounding the vocals, helping them to become clearer and more focussed. If you’ve got access to the mix, however, it’s obviously better to do it the old-fashioned way. Consider using a mid/side EQ for this job as a ‘magic trick’ that you might resort to when your other options have run out.
- Giant lower mids. This one’s great for special effects – try boosting the lower mids in the side channel. It’s an easy way to make something sound huge, without the associated headroom problems or (as much) mix mud. Of course, this technique is often as delicious as it is inappropriate, so have fun with it but remember to go easy in the final mix. A little bit goes a long way.
You’ll notice that all these tips focus on making changes (either boosts or dips) in the side channel while leaving the mid channel (mostly) untouched. This is deliberate – it allows the width to be changed in a way that doesn’t destroy the overall balance of the mix.
With these tips and a bit of practice, you’ll be soon finding your own uses for mid/side EQ.