Space Is the Place, part 1

Dec 1, 2008 12:00 PM, By Myles Boisen

IMPROVE YOUR MIXES BY WORKING IN THREE DIMENSIONS

BONUS MATERIAL
Space is the Place, Part 1 Reverb Parameters Explained

Fortunately, lo-fi recordings with too much midrange seem to have died out with the 4-track cassette and are now relatively uncommon. Much more common is the opposite case — the use of the “smile curve,” named after the segmented visage of a graphic equalizer in which the bass and treble extremes have been boosted and the midrange turned down.

Due to the ear's nonlinear response at quiet volumes (which is demonstrated in the Fletcher-Munson curve), the smile curve approach enables mixes to sound full on small speakers and at low listening levels. However, on a good pair of monitors, a mix that relies too heavily on smile curve aesthetics risks both the low- and high-frequency-based flaws just mentioned.

Filling the Spaces

By now it should be clear that the balance of instruments, imaging, and frequencies lays the foundation for a spacious mix in three conceptual dimensions. It's also important to realize how a change within one of these dimensions can affect and interact with the other dimensional axes in the mix.

For example, shifting the frequency range of a track with EQ not only moves it vertically but also moves it between background and midground positions. Changing the panning can have a similar effect. The simple act of turning a track up or down to change its depth position transforms the frequency balance and affects imaging as well.

Thinking and listening in 3-D like this makes the space between the speakers more of a complex challenge to structure and fill. Not only are there more interactive elements to consider, but with greater listening experience, the gradations of imaging, foreground-to-background relationships, and frequency become finer (see Web Clips 1a and 1b). Ideally, however, these concepts also increase the fun factor.

So far, I've discussed mixing only raw tracks and haven't brought in any of the other tools that define the art of mixing. To conclude the first part of this article, I'll look at reverb and room sound and how these elements can be used to either create space or increase clutter in a mix.

Reverberant Thinking

Perhaps you remember this science experiment from your school days: a container is filled with marbles, and when the teacher asks if the vessel if full, chances are that some members of the class will answer yes. Then sand is poured in, and the sand fills up all the spaces between the marbles. Is the container full now? Don't raise your hand just yet. Water is then added to fill the remaining spaces between the grains of sand.

Like the water in this demonstration, digital reverb is a powerful tool that, if overused, can fill up all the available space in a mix. In 3-D thinking, it's easy to visualize that stereo reverb inhabits not only the horizontal and depth dimensions, but also the vertical frequency spectrum (most audibly in the treble and midrange). By sustaining any or all sounds that already exist in a mix, and doing so in all three dimensions, reverb has the potential to be what I call a primary space sucker.

Of course when used tastefully, reverb can glue a mix together, add a lush professional sheen, and contribute a unique feeling of palpable space. To achieve this ideal of artful reverb use, two things have to be learned: basic reverb parameters and restraint. For those who need a refresher course on reverb settings and usage, see the online bonus material “Reverb 101” at emusician.com.

The Long and Short of It

While reconstructing a mix with clients, I commonly find long hall or plate reverb settings used across the board, and on many more tracks than is necessary. On snare, tambourine, rock guitar, bass, and keyboards, among others, these long-decay reverbs create a murky, sibilant wash that eats up definition and overwhelms background subtleties. When questioned on this practice, the engineer often has no real explanation for why a long reverb was chosen; it just “sounded good” or was a default plug-in setting. For instance, Digidesign's D-Verb plug-in defaults to a large hall setting when opened.

Employing short reverbs keeps the background clear, which also improves imaging and foreground definition. My personal default setting for producing spacious, uncluttered mixes is almost always an ambient or small-room reverb, with a decay of a second or less for most instrumental tracks (see Fig. 3).

Up-tempo vocals also get the ambient or room treatment a lot, often in combination with lively sounding gated reverb or chamber algorithms. In these cases, the decay time can be longer than 1 second, depending on stylistic considerations and mix density.

I tend to use longer concert hall or plate settings only for certain types of ballad or operatic vocals, bowed violin or cello, sustained organ sounds, or any dramatic foreground element that would benefit from a lush, lonely, or haunting reverb tail. Of course, the presence of one richly reverberant track makes it tempting to start sneaking up the reverb level on everything. The end result of this is often a soupy mix that mimics the uncontrollable wash of a school gymnasium.