When mixing acoustic music, your mission is to enhance the instrument and vocal sounds and reinforce the mood of the music, while still keeping the elements sounding natural. Learn how to get the best of both worlds.
By Mike Levine
When mixing acoustic music, your goal is usually to enhance the instrument and vocal sounds and reinforce the mood of the music, while at the same time keeping the elements sounding natural. This approach is particularly applicable to genres like singer-songwriter folk, indie folk, bluegrass, acoustic-inflected country, and country blues, among others.
If you're mixing a pop, hip hop or EDM song and you come up with some wild variation on an instrument or vocal treatment, you have more leeway to use it, as long as it serves the purpose of a song. But in acoustic projects, you’re generally expected to have a lighter touch when mixing.
In this article, we'll offer some tips for various aspects of mixing acoustic-oriented music.
1. Maintain Transients
When you're mixing an instrument such as acoustic guitar, mandolin, banjo or Dobro, the attack of the pick (or fingers in the case of some acoustic guitar) hitting the stings is integral to its characteristic sound. Therefore, when you're compressing such instruments to tame their dynamics, you want to do so with as light a touch as you can get away with and still achieve the dynamics control you’re looking for.
One way to make the compression more transparent is to set slow attack times of at least 12ms or 13ms, and even slower if you can. The more compression you apply, the more the transients will be affected and the slower you’ll have to set the attack.
Perhaps no instrument needs to maintain its transients as much as the mandolin. In bluegrass, it functions as both a melody and a rhythm instrument. For the latter, the mandolinist typically "chops" the chords, which is a percussive, slightly muted strum on the off-beats that plays a similar role rhythmically to a snare drum. So, maintaining its transients is critical.
Example 1: First you’ll hear a mandolin compressed with a fast attack time of .5ms using Renaissance Compressor. When it repeats the attack was slowed to 30ms. Notice how the transients are sharper with the slower attack.
If the track seems lacking in attack, you could even consider using a transient shaper like Smack Attack to enhance it subtly. Also, be careful with the release time. Set it too fast and you may hear pumping as the compressor is triggered and releases continuously.
2. Easy on the Pitch Correction
If you're going to use a pitch correction plugin such as Waves Tune in a song with an organic vibe, such as a folk or an acoustic-oriented country song, you want to keep the speed at which the notes get tuned as slow as you can (which translates to higher values on the Waves Tune speed control). You want to fix pitchy notes without it sounding “tuned.”
You may have to do more note-by-note correcting rather than applying global correction. Just like with compression, you want to come up with subtle settings.
3. Keep Reverb Decays Short
Reverb is another area where a light touch frequently provides the best result. One way to achieve that is to keep the decay time on the short side.
How long you set the decay time depends on the tempo of the song—the faster the song, the shorter the decay time has to be to avoid too much reverb wash hanging over into the next vocal or instrumental phrase.
It's also helpful to use your reverb's EQ controls to reduce the amount of low end on the reverberated sound. You could even roll-off at 200Hz or higher. Doing so will have the effect of lessening how much decaying low-end reverb you hear, which reduces the intensity of the reverb effect. H-Reverb and Abbey Road Reverb Plates have EQ controls built-in, but if you'd prefer to use a separate EQ, insert it after the reverb (assuming you're applying the reverb from an aux track.)
4. One-Size-Fits-All Reverb
If you want to make your studio-recorded mix sound like you tracked it in a club or hall or other performance space, try using just one plugin for all your reverb needs in a mix. For example, a short plate from Abbey Road Reverb Plates, a club from IR-1 Convolution Reverb, or a chamber from Abbey Road Chambers could provide that unifying element that glues together tracks that were overdubbed separately and sound quite different.
You'll also want to use pretty similar reverb send amounts on all the tracks you're affecting, or the differences will be too noticeable. Alternatively, you could just strap the reverb across the master bus and adjust the mix fader.
Example 2: Here’s a short segment of an acoustic instrumental mix. The first time you hear it it’s without any reverb. When it repeats, it has IR-1 with a small hall setting lightly applied to all the instruments—from channel aux busses—to make it sound like they were playing together in the same space.
5. Perform Time Correction Manually
Many DAWs offer sophisticated time-correction features, but it's better not to apply audio quantization to acoustic instruments if you can avoid it. In the vast majority of situations, you don't want to mess with the feel imparted by the musicians on their instruments. Audio quantization can also add unnatural-sounding artifacts to the audio.
Unlike in electronic musical styles, everything doesn't need to be quantized exactly to the beat. If it were, it would sound sterile and lack feel. If notes or hits are noticeably out of time, manually fix them with cut-and-paste editing, rather than using audio quantization.
It's easy enough to cut a bass note and line it up manually with a guitar strum or kick drum hit. That way, you're only affecting a tiny fraction of the part rather than the whole thing, which would happen if you use quantization.
6. Create a Realistic and Consistent Soundstage
If you were mixing, say, a bluegrass band, or other acoustic ensemble, it could be helpful to make your panning decisions by envisioning the group onstage. You'd undoubtedly want the bass and vocals in the center, but each of the other elements can have its own space as if you're watching the band perform.
If you're working on an EP or album, and the instrumentation is essentially the same from song to song, it can be useful to leave the panning of the various players the same throughout for continuity. So, if the banjo player is at 10:00 on one song, leave him or her there for all of them.
If you're trying to simulate that one-mic bluegrass sound, where all the musicians gather around a single microphone, then you'll have to bring all the panning in very close to the center. Keep the instruments and vocals panned a little, but only up to about 1 or 2 o'clock on the right and 10 or 11 o'clock on the left. Otherwise, if you pan all the vocals and instruments straight up the middle, only the effects returns will be in stereo.
7. High-Pass Unneeded Lows
Other than bass—and bass drum and floor toms on a drum kit—most acoustic instruments have their essential frequencies in the midrange and high end. You can make your mixes more airy by high-passing unnecessary lows.
Example 3: To demonstrate the value of high-pass filtering, check out this example. This short excerpt plays twice. The first time, there’s no high-pass filtering on any of the instruments. The second time, all the instruments have been filtered to remove unneeded or unused frequencies.
You certainly want to get rid of any frequencies that are entirely below where an instrument is sounding (for example, high-passing an acoustic guitar between about 75Hz and 120Hz with a 6dB or 12dB slope typically). Use your ears to choose the frequency to start rolling off at. It’s best not to make this decision strictly from listening in solo; check it in context of the full mix as well.
Particularly on a strummed acoustic guitar part, you may want to cut out some of the audible tone at the bottom, which is only adding muddiness to the mix. You can filter it out without hurting the sound of the instrument.
8. Saturate Lightly to Add Depth
It might seem a bit counterintuitive, but subtle saturation can enhance the sound of any acoustic instrument without making it sound "distorted." The best way to go is to dial it in gradually in a parallel configuration like you would with a compressor or reverb.
For example, you could insert Abbey Road Saturator or J37 Tape on an aux track and bring it up on individual tracks using the effects send. Keep the saturation relatively low on the plugin, and slowly bring up the aux send. If you start to hear audible distortion, back off the send a little. Alternatively, you could slightly saturate the master bus, but this way you have more control.
Example 4: You’ll hear a short passage from a mix play twice. The first time without saturation and the second time with Abbey Road Saturator lightly applied on the master bus.
9. Add Attack to Dull Upright Bass
Upright bass is a tricky instrument to record well and can end up sounding too round and lacking the attack of the fingers on the strings. If you're mixing a bass that sounds like that, sometimes EQ doesn't work well enough.
In situations like that, try using a multi-band transient shaper, such as Trans-X, to boost the attack of the upper midrange only. You'll have to play around with the settings, but the 1kHz area is an excellent place to start.
Want more on mixing? Get tips for mixing clean pop vocals here.
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