What is Mid-Side Processing?
To understand where to use M/S Processing, we must first understand what it is. In a stereo field we know that there are two signals, left and right.
Well, any stereo signal that we route at equal levels at the same time appears as a centre image.
Signals that are panned unequally to the L/R channels, appear to the left or right.
In the digital domain we are capable of further separating stereo content into a monophonic “Mid” channel and stereo “Side” channels. This means that you can apply EQ, compression or FX to the sounds in the middle, independently of the sounds panned to the sides. We refer to this technique as mid-side (MS) processing.
Enabling M/S Processing In Logic Pro X
Logic Pro X (with update 10.3) has this functionality with all plug ins.
- Insert a Dual Mono version of the plug in onto your channel.
- In the Plug In header, select configure then configure the mode from “Stereo” to “Mid/ Side”.
Enabling M/S Processing In Ableton Live
With Ableton you can enable M/S directly on EQ Eight, as well as processing your entire Chain.
- On EQ Eight, you just have to enable the M/S Mode.
- Alternatively, open Utility from your Audio Effects and Group.
- Go ahead and select Chain to view your Rack, then add another Utility.
- Rename one Chain to Mid then set the Width to 0%
- Rename the other Chain to Side then set the Width to 200%
Effectively what this means is that if we wanted to, say, Compress the Side signals
separately from the Mid, we would just need to add the compressor to the Side.
So, with all that said, let’s look at this in a few practical mixing scenarios.
1) Lead Vocals
With careful MS processing vocals can seem to be wider.
Turn up the sides and roll off the low end with a shelf of 6 dB at 256 Hz. By doing this we’re effectively EQing the midrange audio to be in the centre, and all of the high- frequency audio will to be pushed to the outside.
When you bring up all the high-end information in the sides and keep the mid and low end focused in the centre, the high-end detail pulls the listeners’ attention to the outside of the stereo field, giving the impression that the sound is wider.
By keeping the mids and low end centred, you make sure that the vocals sit well in the mix, is punchy, and will be mono-compatible.
Generally speaking, low‐frequency instruments such as a kick drum and bass are to be kept in the centre of the stereo field (this is in part down our ears’ inability to localise the source of bass frequencies).
For that reason, many engineers use low cut filters to remove the low end from the sides channel. The exact frequency usually varies according to the content, in some cases it will be as low as 100 Hz, in others as high as 700 Hz.
This ensures that the very lowest frequencies in the mix are all in mono – something that almost always helps tighten up a mix, and also helps to ensure better results when compressing the overall mix afterwards. (See Brainworx bx_digital V3)
Try compressing the low end, around 200 Hz and below, on the mid channel with an attack time set to around 12 ms (in order to allow transients through).
Set your release time to around 60 ms (depending on the track). Roll off a little low end and a little mid-high harshness in the sides channel.
Now compress the low mids in the sides channel with a very fast attack and no makeup gain to create extra space around the kick drum, which should help give a bigger presence in the overall mix.
Next try sending the signal to two aux channels. Set one aux channel to centre only with sides turned all the way down, and the other with sides only and centre turned all the way down.
Once you’ve got the lead synth separated like this, you can insert other plugins or effects on each channel separately.
MS processing can not only help you achieve a more balanced and tighter mix, but with creative uses you can really achieve some wild effects that may be perfect for your track!