When it comes to mastering, the best mixes arrive without the need for much EQ at all, if any. That said there are those times when mixed audio could benefit from some shaping. Where regular stereo EQ has its limits, these three mid side treatments can help.

In Summary

Mid side EQ can shape masters in useful ways based on the stereo picture. These can be more targeted than conventional stereo treatments that register across the entire panorama. Here we demo three uses of mid side treatments for mixed audio.

Going Deeper

Two Channels, Many Possibilities

Stereo always needs two channels to carry the information, with the most familiar format being Left-Right (LR) stereo. An alternative format has been around for as long as Stereo itself which instead sees one channel carrying the mid information (L+R) and the other carrying the sides (L-R). With uses in music, those also familiar will be location recordists and post mixers. Without knowing it, vinyl listening music lovers have also been listening to three-dimensional grooves for decades with mid (vertical) and side (lateral) waveforms stored along a single pathway.

For music, stereo EQ can shape channels and mixes. Sometimes with pre-mixed audio (such as when mastering) it can be useful to choose where in the stereo soundstage EQ should be applied. EQing the Mid channel, or the sides separately can be used to affect changes in musical balance, or to shape the mix to taste more generally.

Using Pulsar 8200 For Mid Side Mastering EQ

In the video below we use Pulsar’s 8200’s mid side capability to massage a master. This software recreation of GML’s legendary parametric tool is an affordable recreation which can be used by ITB mixers and mastering engineers. It’s well suited in this role thanks to its aim of recreating of the original’s especially musical shelves, not to mention the ability to put the analyser away to just listen! We use Pulsar 8200 for the following:

• Bringing out the kick from under the bass in the mid channel without muddying the sides.

• Improving intelligibility in the vocals in the mid channel without lifting the drum overheads in the sides.

• Pushing back the overheads in the sides channel without dulling the vocals in the mid channel.

Pulsar 8220 Features:

• Mid Side mode - For alternative two-channel surgery.

• Metering and spectrum analyser - These can be hidden or shown, for unbiased listening or visual investigations.

• High and low-cut filtering - Unlike the original, this makes no other cut device necessary for losing subsonic clutter or unwanted HF information.

• Tilt filter - Harder to come by in many EQs, tilting the entire response doesn’t risk losing the relationship between bands when overall response needs shifting.

• Air and Sub bands - In a departure from the GML unit’s forward-looking design, these have in fact been developed to provide a response in the style of the Pultec EQ’s shelves.

• Auto Gain - Engineers will be aware of the effect on perceived loudness that equalisation can have. Pulsar’s algorithm uses C-Weighting for its response.

• Gain Scale - Acting as a multiplier for all the bands, this is great for dialling in fine control or broader turns.

More On Mid Side Mastering

Assuming all is well in the mix, the role of EQ across masters is often an artistic one, however more technical fixes can revolve around correcting mixes made through inaccurate monitoring. Often in the low end, these can often be made using a stereo EQ across the entire soundstage. Mid Side EQ can also be used to effect scientific tweaks, and going back to vinyl, dialling down LF energy in the sides channel can help keep the needle in the groove without robbing the entire mix of its foundations.

For those times when subtle changes to the musical balance are wanted, but a remix isn’t possible, the engineer still has options. Although un-mixing and rebalancing tools are getting better all the time, for some, the most natural results are still to be had at the controls of a great EQ. With many hallowed designs out of reach for some studios, using something like Pulsar 8200 can get more engineers pulling some high quality moves inspired by Audio Royalty.

A Word About This Article

As the Experts team considered how we could better help the community we thought that some of you are time poor and don’t have the time to read a long article or a watch a long video. In 2023 we are going to be trying out articles that have the fast takeaway right at the start and then an opportunity to go deeper if you wish. Let us know if you like this idea in the comments.