Of course, no two listeners hear music the same way – a truism easily proven by arguing with Linkin Park fans about what constitutes good rock – and mixing engineers themselves must contend with this subjectivity in our senses. But it often appears that music production lacks any rules; that mixing engineers essentially just follow their whims behind the console.

No “rules,” just “rule”

Indeed, most so-called “rules of mixing” are no more than guidelines. For example, “boost EQ in wide bands,” and “use a slower attack when compressing drums.” Both are great tips, but hardly true in all situations.

However, one overarching principle does apply in every mix, to every song, and to every mixing engineer. I think of it as the Rule of Mixing:

Though it may at first appear trite, this rule simply and powerfully covers the fundamental practices of mixing. A good mix supports the song, presents only what the listener needs to hear, and leaves out unnecessary distractions. Good mixing, in turn, requires keeping the rule in mind at all times to accomplish these goals.

Implications

Some of the rule’s most important implications:

Have a plan
How can you reliably judge which effects and fader moves to keep? In short, by knowing before you start mixing what you want to achieve. Mix with a clear plan in mind for the song, and every change that doesn’t get you closer to this goal is simply not needed.

Don’t use effects “just because”
If you routinely, automatically high-pass guitar tracks, or compress the kick drum and bass guitar, you’re probably violating the Rule of Mixing. Decide before adding one of these effects whether it’s really needed this time. Worded another way: Just because something worked on your last 5 mixes doesn’t mean it’s right for this song.

“Improved” can mean many things
Note that the rule doesn’t say “only do that which improves the sound” (with emphasis on sound.) Sometimes, in order to improve the end result, you need to destroy the sound, for example by adding distortion, or creating a lo-fi mix. This is perfectly OK, if that’s what the song requires.

Mixing starts long before you move the first fader
Taken to its logical extreme, the Rule of Mixing implies that in a perfect world, a mix would require no changes. Just bring the faders up, and you’re done. While that’s obviously impractical, it’s still a great thought to keep in mind when recording. The closer a recorded sound comes to the required final result, the easier it will be to adhere to the Rule of Mixing. This suggests, and not by accident, that you should form your mixing plan even before you start recording!

Favour simplicity
An important corollary to the Rule of Mixing holds that the simpler of two identical-sounding signal chains is always preferable. If you add a plugin but don’t hear a difference, the plugin doesn’t belong in your mix. Whether the effect was too subtle to detect, or your ears simply can’t hear any change, the end result is the same: If you can’t confirm that the change is an improvement, then it’s not needed.

It’s easy to bloat a track with plugins designed to add character or warmth or depth – stereo enhancers, tube and tape simulators, harmonic distorters. But while these tools serve a purpose, their use should always be secondary to your main goal: Improving the song.

Be honest with yourself

More than anything, the Rule of Mixing keeps mixing engineers honest with ourselves. Music is subjective, for listeners and creators alike. But with the constant awareness that every change we make must improve the end result, we force ourselves to think of the mix as a bigger picture.

Phil Spector and Glyn Johns got different end results because they approached their respective mixes with different plans. But both mixes sound great, and emphasize The Beatles’ songwriting, a sure sign that both engineers followed the Rule of Mixing.

See Also: lots more mixing tips!

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A compressor raises the level of quieter elements in a signal. This tends to “fatten” the recorded sound, which can add a lot of character, especially on drums and vocals. However, the effect is most pronounced when the signal is heavily compressed, and over-compression usually kills the dynamics of a performance.

What is parallel compression?

Parallel compression offers a good compromise. In its most common implementation, parallel compression refers to mixing a dry signal with a heavily compressed copy of itself. The dynamics in the dry signal are preserved while the compressed signal adds body and character to the overall sound. It works for any instrument, but on drums and vocals in particular, the added character can really bring a track to life.

This article from Sound On Sound lays out an approach to parellel compression in Logic. (Note, though, that the article incorrectly calls the technique “sidechain compression.” Sidechain compression is an unrelated procedure used to implement ducking, better described here: Sidechain compression in Logic.)

SoS’s method involves duplicating the track on which parallel compression will be performed. I prefer to use a bus or effects send which allows me to pass many tracks through the same compressor, handy for fattening related tracks together. But both approaches produce the same end result, so if your DAW or recording platform doesn’t offer busses or sends, you can still use parallel compression.

Hear it in action

Here’s a short drum passage that I’ll use to illustrate this technique in action:

In this first example, I routed the kick and snare drum tracks to a second mix bus, the parallel compressor (“IIComp” as I call it – see the screen shot below,) and mixed the result with the dry signal heard above:

It’s also obvious that the compressor on the parallel bus is really crushing the signal. For this example, and the one below, I used a Waves C1 compressor with a fast attack, a ratio of nearly 14:1, and a hard knee, as shown here:

This is what the compressed signal sounds like by itself:

While I most commonly apply this technique to the kick and snare only, parallel compression can also be used on the overhead microphones:

Finally, here’s a screen shot to help visualize the signal chain I used:

The kick and snare drum tracks are routed to the primary drum bus (not shown) which carries the dry signal, and to the “IIComp” bus which contains the Waves C1 compressor shown above. Note, too, that the IIComp bus has its level reduced by almost 16db. It’s not necessary to mix the dry and compressed signals at the same level. In fact, doing so usually defeats the purpose of using parallel compression as the compressed signal overpowers the dry signal and smears its dynamics.

Other approaches to parallel compression

The examples above show the most common implementation. However, there are as many ways to set up parallel compression as there are ways to configure a compressor. Different attack and release times create different effects, as do different ratios. In my examples, I used a fast attack and slow release, which removes all the transients from the signal. However, with a shorter release time, you can create a “pumping” effect which often adds a distinctive sound.

Further, different compressors have different characters. The free Blockfish compressor, for example, is great for crushing a signal beyond recognition. And when mixed at low levels under a dry track, this “distressed” signal usually adds complimentary qualities.

As with all recording techniques, of course, experimentation is the key to finding sounds that work for you.

UPDATE: See Andy’s comment below about using this technique in a DAW that lacks latency compensation

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for more compressor techniques, and drum recording tips.

Previously: More on compression, Better drum mixes

When it comes to individual tracks, it is pretty much routine to compress vocals, bass guitars, acoustic guitars and occasionally electric guitars, though overdriven guitar sounds tend to be self compressing anyway! The most important of these to get right is the lead vocal, because even modest dips in level can make the Iyrics difficult to hear over the backing.

The article is ten years old, so it deals with hardware compressors rather than plugins, which were essentially unheard of in 1996. But the principles of dynamics control haven’t changed, so the article is still relevant.

He also offers a handy chart of useful compressor settings. While the chart obviously can’t replace the judgement of your ears, it’s a good starting point for novices who find themselves preplexed by the possible combinations of attack, release, and threshold.

parralell[sic] compression is when you double a track and compress one copy very hard, and mix it under the original. It preserves the dynamics of the instrument but makes it sound more solid.

Help me learn to properly mix tracks.

The key lesson I learned was to use EQ to give each instrument its own clear part of the audio spectrum. If the bass is filling the low frequence, CUT BASS on everything else. Cut treble on the bass. Think of the mix as a jigsaw puzzle of frequencies, with each instrument filling a part of the puzzle.

Widening a mix:

As a sound moves further away, the treble dies away faster than the bass frequencies, so the sound becomes less clear. This is the case when using reverb; a really distant sound has very little high frequency content in the reverberated signal reaching your ears. In terms of dynamics, distant sounds are dynamically flat; ie, very compressed, whereas close up sounds are uncompressed and have strongly varying dynamics.

If you charge someone for your time as a recording or mix engineer, don’t undercharge:

$20/song is absolutely unacceptable. From what everyone has been saying, numbers like that really tend to hurt the industry, especially for engineers and studio owners. I live in Orlando, FL and there’s a guy down here (I won’t name names) that runs a studio called Gridlock and charges $700/song. And to be honest, for his level of work and list of credentials, that is still a damn good deal.

It shows the fundamental and harmonic ranges for more than 25 instruments (including drums,) along with the perception each creates (“boom”, “warmth”, “crunch”, etc.) in various segments of the audio spectrum. Tufte would be proud.

You can also download “Compression uncompressed,” a detailed ebook on compression techniques, from the Independent Recording Network’s main page.

[Note: updated 01/16/2007 with new permanent address. Thanks Glen]