Are You Listening? S2 Ep.1 | Stereo Imaging in Mastering: Width and Mid/Side

Are You Listening? S2 Ep.1 | Stereo Imaging in Mastering: Width and Mid/Side

Matthew Vere
Matthew Vere

Table of Contents

Optimising Your Room for Stereo Width Perception

If you hear sounds that you perceive as emanating from outside your speakers, these are reflections off the surfaces or objects in your room, affecting the perception of stereo width.

Listen to the sides of your reference tracks and ask: what instruments are panned, and to what extent? Listening to just the sides will reveal only the panned information of that track. The same goes for the mid signal; this is the information not panned, or in mono.

The essential elements in a mix should be in the centre, vocals can be spread out but are most dominant as the central element.

Implications of Stereo Widening

Every time you adjust the side information, pay attention to what's happening to the mono information of the track. There are always trade-offs that you need to monitor and be aware of.

Should You Mono The Bass?

Mono-ing the bass in mastering can be a bad idea, as it brings all the low energy from accompanying instruments and sits them over the bass and kick drum in a mix. This may or may not be a good thing. You're going to lose some stereo depth in the low to mid-range but gain back some clarity. This happens because you've taken out low energy from the sides, and brought it into the centre.

Think about what you're doing, and why you're doing it before you mono the bass.

Stereo Width in The Signal Chain

Make stereo imaging corrections first, before any other signal processing. Modules in a signal chain are dependent on the level coming out of the previous one.

Stereo imaging adjustments (not corrections) should be made around the second to last module, before the limiting.

What Kinds of Instruments Should You Pan?

Tonal instruments that carry harmony, that are complementary to the featured instruments. Percussion instruments or the ear candy that defines the edges of the stereo field.

It's a good practice to be careful of raising the side information in the mid-range. This can create competition between the elements sitting in this area.

You can make more significant stereo changes to the top end of a track, as these elements aren't interfering with the main instruments as much.

There are always trade-offs when deciding how wide to push a frequency band, that you need to be continually managing.

Understanding Stereo Width in Metering

The more the vertical orientation, the stronger the mono component.

The more the horizontal orientation, the stronger the stereo component.

If you see a stronger horizontal than vertical orientation, you may have too much information panned or need to bring up the information in the centre.

MV: Future explanation:

At this stage, you may be wondering what mid/side means. How can you have side information in audio? In stereo, we have two channels left, and right, how does the mid/side equation relate to this?

Mid-Channel is L+R, the Side channel is L-R.

On a correlation meter (that measures the stereo and mono relationship), you will see these values:

+1 = Mono signal (information that matches in both the L + R channels, or, the information that's in correlation.)
-1 = Stereo Signal (information that does not match between L + R channel or the information that's out of correlation.)
0 = In between the two above values, not entirely in phase or out, somewhere in the middle. In phase or out means, they match or do not match.

The +1 measure is assessing the difference between the two L & R channels; when they match, we have what's called a positive correlation.

The 0 measurement indicates a wider stereo field, a wider discrepancy between the L & R channels.

Then the -1 measurement tells us that the L & R don't match at all and that the track won't work in mono, at least, not to the extent it does in stereo. By won't work, I mean some sounds and frequencies will be missing, masked, or both. The -1 measurement is emphasising the mono-compatibility risks you're taking.

I hope that clears up any confusion.

Back to the tutorial notes:

The Importance of Checking Your Mix in Mono

Is the listener going to hear what you intend them to hear?

You want your essential instruments to not disappear or change widely in volume when your mix plays in mono.

If you take a stereo mix and de-correlate it, the music will soften. This happens because there is a power that comes from two speakers performing identical movements simultaneously. If you take a kick drum and pan it to one speaker, or one side, you lose power, loudness and energy.

But, feel free to go on artistic adventures with stereo imaging.