T. 4 Gestión de conflictos y toma de decisiones

Dynamics processors have two typical functions in mixing: (1) they may con- trol fluctuations in volume by either reducing the dynamic range (compression/ limiting) or increasing the dynamic range (expansion/gating) while remaining relatively transparent in regards to the overall timbre of the audio; or (2) they may significantly alter the timbre and be used as an audible effect that also in-

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fluences the dynamic range of the audio. I have already covered the dangers of using too much compression in chapter 3, so here I focus on the more advanta- geous ways compression gets used in mixing.

Dynamics for Volume Control

Controlling the volume through the use of compression is standard practice on many elements in a typical popular music mix in all genres. There are often a large number of instruments and voices in many popular music tracks making it especially challenging to keep elements such as lead vocals, bass, and drums present throughout the mix. A reduction in the dynamic range through the use of compression allows the mixer to avoid having to turn up these elements rela- tive to others in order to maintain their presence in the mix. Typical examples include lead vocals where the quiet words might get lost or the loud words stick out too far above the band. With compression, the vocal will remain more au- dible at all times and maintain a consistent and comfortable level in relationship to the band. Similarly, with the bass; we generally want the bass to be present at all times, without the loss of support that might happen if the level dips too far or the conflict with other elements if the level jumps too high.

Strategies for compression usually start with a single compressor set to a moderate ratio (between 2:1 and 5:1) and with the threshold set so that the loudest sounds achieve about 6 dB of compression (gain reduction). The type of compressor to be used and the setting of other parameters (attack, release, knee, etc.) will depend on the nature of the program material and the desired effect (more on this in chapter 6’s review of processing different elements in your mix).

More pronounced compression might best be achieved by using two compressors in tandem. A typical strategy might be to compress peaks first and then level the output using a compressor that is reading the average level (RMS), or the opposite if more dramatic leveling is desired. Similarly, you may want to compress peaks during recording for both initial dynamics control and some overload protection, and then use an RMS style compressor during mixing. It is not uncommon to use as much as 15 dB (or more!) of total compression on a lead vocal, and this is best achieved in two stages rather than by pushing the threshold to such a dramatic extent with a single processor.

It has become increasingly common for extreme compression to be achieved through the use of traditional limiters and brickwall limiters. High- ratio compression produces more distortion and unnatural artifacts, but it is remarkable the extent to which contemporary processors can achieve extreme dynamics control and maintain reasonable transparency of sound. Extreme compression certainly places audio “in your face.” This might be seen as a posi- tive (lots of impact) or a negative (no relief). Whatever your aesthetic judgment, this kind of process suggests the next topic—dynamics for effect.

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But first, listen to the following audio clips to compare the use of com- pression.

Artist: Mike Schermer CD: Be Somebody Track: “Corazon”

Audio Clip 4.13 A brief clip with no compression on the lead vocal. Audio Clip 4.14 The same clip with moderate compression on the

lead vocal.

Audio Clip 4.15 The same clip with extreme compression on the lead vocal.

Dynamics for Effect

Relatively extreme dynamics settings go beyond traditional volume control to produce very audible changes in the timbre of sound. The most common and obvious of these is the effect of a lot of compression on drums, and I will cover the specifics of that in chapter 6 on mixing drums.

To understand how compression and limiting can create very audible ef- fects, you might consider a rubber ball. If you compress a rubber ball, you are concentrating the energy of that ball into a small space. A highly compressed rubber ball will bounce with much greater energy than a ball with the same mass but greater volume. Similarly, compression of the dynamic range of a sound has concentrated the sonic energy. This explains the kind of explosive drum sounds that are produced with large amounts of compression.

Even small degrees of compression concentrate the energy in ways that give audio more immediate impact—a more “in your face” quality. Combined with the advantages of a more consistent presence in the crowded environment typical of so many popular music mixes, compression becomes both very ap- pealing and a virtual necessity. The unfortunate result has been too many cases of over-compression, where expressive musical dynamics lose out to the desire for the immediate impact created by excessive compression.

Parallel Compression

A popular strategy for gaining some of the advantages of aggressive compres- sion without the excessive loss of musical dynamics is parallel compression. Com- pressing in parallel means using two “parallel” tracks of the exact same audio in order to compress one of the tracks and not the other. You can then balance the compressed signal with the uncompressed signal to create a blend. Or, if your compressor plug-in has a wet/dry control as is increasingly common with new compressor plug-ins, you can balance the uncompressed signal (dry) with the compressed signal (wet) in order to implement parallel compression.

Parallel compression allows you to use extreme compression settings but to avoid the very unnatural effect of those extremes because you blend them with the uncompressed (or even lightly compressed) signal to gain the advan-

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tages of extreme compression without the obvious side effects. If you use a very low threshold, so that you might be hitting 20 dB of compression or even more, you can use a low ratio (2:1 or less) and still have a highly compressed signal that, when mixed with the original signal, can greatly increase the presence, or “in your face” quality, of a track.

Typically you would want a fast attack and slow release to create even com- pression and to avoid some of the unnatural pumping caused by the return of level after compression. Higher ratios (with low thresholds) will produce even more dramatic effects along with the heavy pumping caused by the return of the uncompressed level. It will also start to produce distortion (which may or may not be desirable). Parallel compression used in this way gives a great degree of fine control over the effects of compression.

If you EQ the signal going into the compressor channel, you can use the compressed signal to emphasize certain frequencies. For example, if you feel the original sound is a little thin, a little sibilant, and/or overly bright, you can low-pass the signal feeding the compressor and can get a warm and rich sound without much high-frequency information, but with the increased presence provided by the compression. You can combine as much of that with the origi- nal signal as you want, and then feed that back into the original sound—adding body, warmth, and presence to the original signal.

Because of the latency (delay) caused by plug-ins, it’s important that you either employ delay compensation or, if that isn’t available to you, use all the same plug-ins on both tracks, bypassing the compressor on the uncompressed track, in order to keep the two tracks phase aligned (plug-ins generate the same latency in bypass mode as they do when they are in operation).

The Individual versus Cumulative Effect of Dynamics in Mixing

Good mixing requires that attention be paid to both the individual and the cu- mulative effects of dynamics processing. It is here that compression for level control and compression for effect may overlap as subtle compression on many individual elements, on subgroups, and on the stereo buss can combine to pro- duce a very audible overall effect; see diagram 4.1. Even on mixes where there isn’t any element getting a heavy dose of compression for effect, the cumulative effect might well be very audible; see diagram 4.2.

DIAGRAM 4.1

The chain of processors in a typical mix that combine to create the cumulative effect of compression and limiting.

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Check out this audio clip and see the section later on stereo buss processing. Artist: Claudette King CD: We’re Onto Something Track: “Can I

Walk You to Your Car?”

Audio Clip 4.16 A brief clip of a final mix.

Audio Clip 4.17 The same clip with all the compression removed.

CREATIVE TIP

Finding your aesthetic perspective

From an aesthetic point of view, the cumulative effect of compression might be considered the element that binds all the pieces together, that makes the track “gel” and “sound like a record,” as opposed to a less “finished” demo. It does this at the expense of a certain rawness, a “natural” quality, and a broader musical expressiveness that are a result of musical dynamics. The trade-off between impact and expression when using compression reflects the aesthetic balance that recordists wrestle with in creative mixing.

Like many recordists, I mix in a variety of genres, and I find that some artists respond very negatively to the cumulative effects of compres- sion and some very positively. Typically this is genre-based—roots musi- cians and chamber musicians may dislike the cumulative effects of com- pression while contemporary pop, rock, and hip-hop musicians may love it. On the other hand, you may discover the opposite to be true. It would be very rare for me to mix anything without any compression—I think it’s an almost essential element in transforming a live music environment into a recorded environment—but the extent of compression represents a critical aesthetic choice.