With mixers delivering for an ever-growing list of platforms and playback devices, keeping tabs on the mix’s technical health has never been more important. Here are our five essential checks and why they matter.

In the days of a more devolved industry, things used to be somewhat simpler for the mix engineer. The mix would be completed largely to satisfy artistic and subjective needs, on the understanding that staying in the sweet spot on the console’s VU meters would take care of the technical side. The resulting ‘print’ would then go on to the next person or team, seeing different people along the way concerned with mastering, distribution, and sales.

Thanks to advanced production tools, the path from mic to earbud has been radically shortened. Most would agree that the defining quality of any audio mix is still in its sound, however, it must be said that creating mixes has become as much about satisfying technical considerations as it has aesthetic ones.

In this new paradigm, the listener often finds themself only one or two people removed from their favourite artist, with the engineer in the middle. With this person frequently wearing the hats of mix engineer, mastering engineer, and distributor. We list here our essential mix checks to keep audio in shape and ready for the world. While primarily aimed at music mixers, much of it can apply for those producing post production deliverables as well.

1- An Alternative View

Although already high on most engineers’ radars, worthy of mention is a more subjective check. Listening on a second, alternative pair of loudspeakers is invaluable for getting a valid basis for comparison. This can easily reveal the shortcomings of other monitoring devices or decisions arising from their use, as well as an indispensable ‘consumer-ear-view’ affording correction where needed. This also extends to including earbuds and other devices. Doing this can reveal spectral inconsistencies, but perhaps even more useful is getting an extra window on levels in the all-important middle.

2 - Quality Counts

The fact remains that forgoing all of the complexity involved with producing deliverables, the things that will actually trip up distribution are more banal. While getting the more quantitative factors right is important, services and distributors might not always reject deliverables based on less technical aspects. In many cases the engineer can be the final judge of quality, and perhaps more damaging to the final product are any oversights surrounding problems that could get through such as clicks, pops, noise, chopped reverb tails or digital clips. Listening critically (perhaps on headphones) for these is an essential ‘QC’ job, and those self-mastering and/or self distributing should listen twice on the proviso that they can only release once…

3 - Louder, Better?

In recent years, services’ introduction of loudness normalisation has brought about a huge cultural shift regarding engineers’ attitudes surrounding mix levels. With most understanding that over-loud masters now equate to subjectively ‘smaller’ sounding, level-reduced playouts, the smart money is on mixing to the service(s) target loudness level(s) for optimum listening enjoyment. While opinions vary on whether or not to mix into compression from the outset, avoiding pitfalls such as mixing into limiting (where small momentary fader moves can provoke enormous limiter intervention), and using loudness-aware metering from the outset all conspire towards better-sounding masters. For a refresher on this essential audio knowhow, you can read our in-depth guide to loudness right here.

4 - Seeing Spectra

Along with level metering, the humble DAW waveform is perhaps the most recognised form of audio represented visually. This ‘trace’ of amplitude over time can give a representation of frequency as well, and many will recognise stretched out lower frequencies opposed to the density of higher ones.

Much has been written regarding mixing with the aid of dedicated spectrum analysers, or the related Spectrogram. While the former displays frequency against level giving the familiar ‘electric skipping rope’ readout, the Spectrogram adds a third metric of time, with frequencies’ levels represented by colour and brightness. While analysing spectra visually cannot report what the music sounds like, tools such as spectrograms can show up errant frequencies (such as subsonic sounds that eat headroom) that your monitoring system could be keeping to itself.

5 - The Narrow View

More recently, mono playback at the consumer’s end has been back on the menu thanks a new slew of smart speaker devices for the home. While many of these can be paired up for stereo, a great deal of single devices fold stereo mixes down into mono. At its simplest, checking deliverables in mono before bouncing will show up any compatibility problems as reduced or missing levels on certain voices and/or instruments.

Taking a more analytical approach, using a correlation meter or phase meter can report potential problems before any buttons checks are made. Many consoles have these, with countless audio plugin versions taking their design and expanding upon them, including Flux’s excellent, free Stereo Tool.

You can read more about the feedback from this kind of check here, but in essence this kind of metering shows when signals that should be similar (correlated) in both channels are at different points in their cycles arising from phase issues. These can take a number of forms, with over-wide sources such as stereo mic pairs or reverb returns being common culprits. Certainly any mix-widening should be used in conjunction with the humble mono check.

Anything Else?

It can be revealing to compare the sound of different audio codecs. That said, if the destination service determines which one (if any) is used, then any time deliberating over which one sounds best may better spent elsewhere. For when comparisons for different versions are needed, techniques using polarity may be used, or for in-depth analysis, a tool such as Nugen’s MasterCheck Pro allows realtime comparison of codecs, as well as Delta monitoring of artefacts only.

While discussions about the artist’s ability to self-master will continue, those finding themselves at the end of the chain have never had a broader range of tools to get mixes ready for the world. For everything else, theres also the simple pleasure of taking some time away, coming back, and listening with a friend.

Photo by Caught In Joy on Unsplash