Anyone who has ever mixed a piece of music knows how important ambience is. Adding space to an instrument or to a vocal track can bring it to life and give it a sense of depth. For many years, delay and reverb were used heavily and often without much subtlety. From the tape slap and echo chambers used in '50s music to the over-the-top effects of '80s pop, conspicuous ambience was frequently applied.
Musical tastes have changed since the '90s, and it's become fashionable in pop music to mix the vocals drier. Clients and producers specifically request less reverb, but they still want to hear space around a vocal, a dramatic coloration for a solo instrument, or a heightened sense of separation between foreground and background. Applying ambience has become trickier than it was in the old days you can't just crank up the reverb send anymore. Instead, you have to be subtle and use a range of techniques.
This article discusses ways to tweak reverbs and delays to create other ambience options that go beyond the same old thing. Chances are that your current setup has the potential to dial in unusual and original effects.
Reverb and delay are the two basic building blocks of ambience. Reverb is designed to simulate the sonic characteristics of a real physical space: room type, size, and surface. After selecting an appropriate setting, you can then determine its virtual size by manipulating the decay time.
One way to achieve a subtle yet effective ambience is to drastically reduce the decay time of a reverb patch. More intense presets such as churches, large plates, or concert halls which typically have decay times of three to four seconds work best for achieving subtle ambience. Decrease the decay time to 0.5 seconds, and increase the predelay to 100 ms or more to create a sound that's spacious without being wet. That technique allows you to retain the sonic character of the space in a shorter, more concentrated package, although you may have to increase your send levels to make those effects work in your mix.
Many reverbs also include EQ controls. Highpass and lowpass filters are the norm, but some processors have even more elaborate EQ capabilities. Using a lowpass filter to reduce the high-frequency content of the ambience can quiet a noisy track. Cutting highs in the reverb on an acoustic guitar track, for example, can subtly deemphasize occasional finger squeaks. Similarly, a not-so-bright reverb may be a better choice for a snare track that has lots of hi-hat leakage. At the other end of the sonic spectrum, adding highs to a short, intense reverb can increase the impact of the effect.
More elaborate reverb processors allow you to go even deeper and manipulate the balance between the room reflections (called early reflections) and the sustained reverb sound. You can experiment with creating ambiences that are all reflections, all reverb, or a blend of your choice. Experimenting with ambiences also allows you to see how your processor is able to simulate so many different spaces with so few controls.
When working in a DAW environment, it's always tempting to use multiple instances of your most expensive reverb plug-ins the ones that have the most features and the longest list of presets. Unfortunately, those plug-ins can significantly tax your CPU. Even if you have a reasonably powerful system, you may still need to find effects alternatives as you run out of processor power. One way to lower CPU usage is to set up the reverb as a bus effect and send multiple tracks to the same plug-in, rather than using individual inserts that require an instance of the plug-in for each insert. You can also bounce tracks to disk or freeze them once you've applied effects.
Another way to save CPU resources is to use two instances of a power-efficient mono reverb plug-in to create a unique stereo effect. That approach offers interesting sonic possibilities and also works with hardware processors. If your hardware effects unit has multiple effects engines, then you can build a powerful stereo patch with an individual engine dedicated to each side of a stereo return.
Whether in software or hardware, start with each side of a stereo return set to the same patch, and then modify one side. One way to accomplish that is to add a hefty amount of predelay, which results in the reverb sounding as though it's moving across the stereo spectrum. Keep in mind that the ambience doesn't have to be symmetrical. If you choose a predelay time that has an exact rhythmic relationship to the tempo of the song, then you can create an ambience that throbs with the beat.
Delay times that are synchronized with a song's tempo can help generate bounce and flow in a mix. To make that happen, you'll have to accurately compute the delay times that fit your song's tempo. Many delay plug-ins automatically calculate that for you. If, however, you are using a hardware-based processor or your song was recorded into a DAW without a click, then you may need to calculate the delay times. Shareware or freeware delay calculators are available on the Web (you'll need to know the song's tempo to use them), or you can use simple math.
If you mix live music, then you may have developed a knack for turning the delay knob at the right moment to send a phrase or word into a sonic spin. When mixing in the studio, however, there are more accurate ways to set a delay to kick in at a precise moment. In a DAW environment, one method is to generate a dedicated delay-effect track. This is an excerpt from the following article: Ambience Clinic.
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