If this goal doesn’t emerge until mixing, you’re not out of luck.
A simple reflection can often be just as useful as a well-performed double.
Try a static 80-110 ms slap-back delay panned left to provide symmetry for the right-panned background vocal elements. Be sure to vary the delay time for the complementary right-panned delay by at least 10 percent.
If this technique introduces too much depth (perception of distance), a much shorter delay time (20-40 ms) can be used.
Just be sure to introduce a little slow modulation to these shorter delays to avoid unpleasant static phase problems.
3. Group Processing
Whether your goal is a mono layer of lead vocal content or a supporting stereo vocal instrument, the objective is to get a group of individual audio tracks to behave as a single instrument. Group processing is a simple and effective way to achieve this.
For example, one big difference between the sound of a beautiful stereo vocal pad and ‘just a bunch of vocal tracks’ can be shared dynamics. A stereo-linked compressor across a background vocal subgroup will help create both dynamic and tonal homogeny within the group. Processing the constituent tracks individually can’t provide the same affect.
Similarly, a mono vocal layer (like a hip hop lead and its doubles) often needs attention in the midrange to make sure it has a focused place in the track. Doing that EQ work in a subgroup can help strengthen the perception that these individual tracks are a single, tonally complex, musically powerful instrument.
Start with a Plan
It’s never too early in the process to begin considering these ideas. A well-produced overdub session has a way of taking hours off of the mixing process.
Of course these techniques can apply just as well to other types of tracks like guitars, horn sections, and keyboard layers.
Each application might have its own idiosyncrasies, but the concepts are the same.
Rob Schlette is chief mastering engineer and owner of Anthem Mastering (anthemmastering.com) in St. Louis, MO, which provides trusted specialized mastering services to music clients across North America.
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