Tech Tip:Beyond Level Changes with Mixing
By Craig Anderton
When mixing, the usual way to make an instrument stand out is to raise its level. But there are other ways to make an instrument leap out at you, or settle demurely into the background, that don’t involve level in the usual sense. These options give you additional control over a mix that can be very helpful.
Changing Start Times Changes Perceived Loudness
The ear is most interested in the first few hundred milliseconds of a sound, then moves on to the next sound. This may have roots that go way back into our history, when it was important to know if a new sound was leaves rustling in the wind – or a sabre-tooth tiger about to pounce.
What happens during those first few hundred milliseconds greatly affects the perception of how "loud" that signal is, as well as the relationship to other sounds happening at the same time. Given two sounds that play at almost the same time, the one that started first will appear to be more prominent. For example, suppose you have kick drum and bass playing together. If you want the bass to be a little more prominent than the kick drum, move it ahead of the kick. To push the bass behind the kick, move it late compared to the kick.
The way to move sounds depends on your recording medium. With MIDI sequencers, a track shift function will do the job. With hard disk recorders, you can simply grab a part on-screen and shift it, or use a "nudge" function (if available). Even a few milliseconds of shift can make a big difference.
Creative Use Of Distortion
If you want to bring just a couple instruments out from a mix, patch an exciter or "tube distortion" device set for very little distortion (depending on whether you’re looking for a cleaner or grittier sound, respectively) into an aux bus during mixdown. Now you can turn up the aux send for individual channels to make them jump out from a mix to a greater or lesser degree.
Tubes As Processors
Many members of the "anti-digital" club talk about how tube circuitry creates a mellower, warmer sound compared to solid state devices. Whether you agree or not, one thing is clear: the sound is at the very least different. Fortunately, you can use this to your advantage if you have a digital recorder.
As just one example of how to change the mix with tubes, try recording background vocals through a tube preamp, and the lead vocal through a solid-state preamp (or vice-versa). Assuming quality circuitry, the "tubed" vocals will likely sound a little more "in the background" than the solid-state ones. Percussion seems to work well through tubes too, especially when you want the sound to feel less prominent compared to trap drums.
Pitch Changes In Synth Envelopes
This involves doing a little programming at your synth, but the effect can be worth it. As one example, take a choir patch that has two layered chorus sounds (the dual layering is essential). If you want this sound to draw more attention to itself, use a pitch envelope to add a slight downward pitch bend to concert pitch on one layer, and a slight upward pitch bend to concert pitch on the other layer. The pitch difference doesn’t have to be very much to create a more animated sound. Now remove the pitch change, and notice how the choir sits further back in the track.
With a hard disk recorder, you can do little fade-ins to make an attack less prominent, thus putting a sound more in the background. However, if you do a fade starting from the beginning of a sound, you’ll lose the attack altogether. Instead, extend the start of the fade to before the sound begins (Fig. 1).
After applying the fade-in operation, the audio doesn’t come up from zero, and the attack will be reduced.
One common technique used to strengthen voices is doubling, where a singer sings a part then tries to duplicate it as closely as possible. The slight timing variations add a fuller effect than doubling the sound electronically. However, panning or centering these two tracks makes a big difference during mixing. When centered, the vocal lays back more in the track, and can tend to sound not as full. When panned out to left and right (this needn’t be an extreme amount), the sound seems bigger and more prominent. Some of this is also due to the fact that when panned together, one voice might cover up the other a bit. This doesn’t happen as much when panned.
Chorusing As Kryptonite
If you want to weaken a signal, a chorus/flanger can help a lot. Set it for a short delay (under 10 ms or so) and use an out of phase output mix (e.g., the output control that blends straight and delayed sounds says -50 instead of +50). Alter the mix by starting with the straight sound, then slowly adding in the delayed sound. As the delayed sound’s level approaches the straight sound’s level, a comb-filtering effect comes into play that essentially knocks a bunch of holes in the signal’s frequency spectrum. If you’re trying to make a piano or guitar take up less space in a track, this technique works well.
Mixing VIA EQ
EQ is a very underutilized resource for mixing. Turning the treble down instead of the volume can bring a track more into the background without having it get "smaller," just less "present." A lot of engineers go for really bright sounds for instruments like acoustic guitars, then turn down the volume when the vocals come in (or some other solo happens). Try turning the brightness down a tad instead. And of course, being able to automate EQ changes makes the process go a lot more easily.
Overall, when it comes to mixing you have a lot of options other than just changing levels – and implementing changes in this way can make a big difference to the "character" of a mix. Have fun adding some of the above tips to your repertoire.