The Lowdown on Low End, Part 2: Mix Techniques
It’s always essential to get the low end of a mix dialed in just right, because a lack of balance here can divert the listener’s attention, reduce the emotional impact of a song, and compromise the entire production.
Image by Flickr user Bryan Debus
As we covered in The Lowdown on Low End, Part 1: Monitoring, this already-daunting task is made even more difficult if your workspace fails to provide you with accurate playback.
But even in the best of circumstances, a few key tricks can help ensure maximum impact and balance for your bass frequencies.
References
It’s paramount to have good commercial references easily accessible at all times, and to consult with them often.
After listening to the same thing for long enough, our ears begin to adjust, and our perspective will become skewed. Not convinced? Try lowpassing your mix bus around 10k and working for 10 minutes, then bypass. Holy brightness!
Your rotating portfolio of commercial reference mixes should be of high caliber and contain tracks across genres that are bass heavy, bass light, and bass neutral so that you can aim to land in the range of this spectrum best suits your production.
This is a matter of taste as much as technique, and where you’re just getting to know an artist, it can be helpful to get a sense for what commercial releases sound really “right” in the low end to their ears. What they can’t describe in words, they may be able to describe through example.
Re-Arranged
If you’ve got five elements fighting for real estate in the low frequency zone, it’s probably time to question the instrumentation and arrangement of your production.
If there’s a bass guitar, sub bass, synth and kick drum all competing for space in the low frequencies, it’s almost certain that you’ll spend much of your time sifting through a whole lot of mud.
This is best approached at the tracking stage, as a mixer may not always feel comfortable questioning the arrangement once it’s completed. But, if you’re presented with a cluttered low end, it’s integral you decipher which elements need to carry the lion’s share of lowest frequencies.
EQing for Impact
It’s especially essential to determine which specific element will sit the lowest in the frequency spectrum. This is usually going to be the kick drum or the bass.
Chances are that the slower or more sparse of these two will want to have its bottom octave sit lowest in frequency, perhaps in the 40Hz-90Hz range, while busier of the two will want to have its lowest frequency sit a bit higher—often in the 80Hz-180Hz range.
Once you figure out which instrument should be the lowest and which should be the second-lowest, let each one rule the roost in its domain.
Don’t be afraid to use shelving or high pass filters on other bass instruments to make space for the lowest bass instrument. And don’t be shy about clearing room for the second-lowest bass instrument by using targeted EQ dips on a competing bass instrument.
So often, a strategic cut to the lows of one bass instrument can open up the bottom end, making other bass instruments feel much larger and more impactful overall. Remember: In the end, there can be only one dominant instrument in each area of the lows.
Sweeping
High-pass filtering is an invaluable tool for sculpting lows, and it can also free up a great deal of headroom. But it’s useful for more than just that.
If you ever find yourself not really knowing where to start when addressing the low end, it can be helpful to low-pass the entire mix bus and sweep around 100Hz and lower to identify what’s working and what’s not.
You’ll quickly discover where your problems start, and where they end. And, if you can make your lowest instruments audible when hi-passing the whole mix, you know you’re doing something right.
Sidechaining
Equalization isn’t the only way to create space: Sidechaining low frequency instruments to the kick drum can be a very effective method for carving out space in the bottom end using dynamics.
Sidechaining elements to the kick drum can also up the excitement level of your mix as a whole. This works not just for bass instruments, but also for guitars and synths that live primarily in the midrange frequencies. You’ll find this technique is used often in contemporary pop and EDM productions.
Perfect Pitch
A classic technique worth exploring is tuning the kick drum to work well within the key of the song you’re mixing. If you end up layering your kick with any samples, it’s worth noting whether the pitch of the sample plays well musically with the rest of the tune. Sometimes a subtle shift in pitch is enough to make a kick and bass “gel” better together.
For example, if you’re mixing a song in the key of C, and your kick drum’s fundamental frequency happens to be around 65Hz, there’s a chance the bass will visit that note (thus the frequency of “C2” at 65.41Hz) throughout the song. One may not be able to employ this technique often, but it’s good to be cognizant of these kinds of relationships, even if only in the back of your mind.
Harmonics
If you do find yourself in a situation where multiple elements are fighting for the same real estate, harmonics can be a major ally in these scenarios. Maybe 65Hz has been claimed primarily by the kick drum, however a tasty boost for the bass at 130Hz can go a long way, or vice versa.
It can be helpful to use saturation to drive up the harmonics in a bass signal to give it some more presence above the fundamental frequency. Distortion plugins have come a remarkably long way in recent years, so far in fact that mix wizard Tchad Blake claims not to have re-amped a signal since the SansAmp PSA-1 plugin made its debut in the early 2000’s. Harmonics are such an effective tool that they can potentially replace the need for EQ and compression in certain situations.
Check Your Head
It’s the frequencies around 100Hz and below that tend to take up the vast majority of available headroom on your mix bus, so it’s crucial to EQ and filter wisely to maintain headroom.
You may have gotten an earful from your mastering engineer at some point urging you to be cautious with your EQ moves down low. A general rule of thumb is “If you can’t hear it, don’t boost it!”
In addition to the fact that unnecessary (and inaudible) low end information can cause your compressors to react undesirably, it’s also much more difficult for a mastering engineer to clean up a messy low end than it is for them to add a bit more weight in the right places when necessary.
One good way to ensure you’re not including any unnecessary low end information in your mix is to high-pass filter everything that doesn’t have or need substantial lows. Even if this filtering seems inaudible on your system, you’d be surprised at the kinds of nuisances such as machine noise, outside traffic, and bumping of mic stands that may be lurking down there unbeknownst to you.
In Phase
Some additional points to keep on your radar are phase and delay compensation. If you’re working in a DAW that doesn’t offer automatic delay compensation (ADC) you must be extremely mindful of the plugins you choose and how they tax your processors.
If you’ve got a bass DI and a bass amp that are time aligned but a plugin is setting one back 30ms, your lows will hollow out. The same goes for if you’re doing any parallel processing on your drum bus, where you’ll hear dramatic unpleasantries across the entire frequency spectrum.
If you’re layering any of your recorded drums with samples, it’s wise to examine their waveforms visually. Once your shells are in phase with your samples, be sure to check them against your overheads and room mics to make sure there is no cancellation there either.
The Bottom Line
Unbalanced low end is a tell-tale signature of the inexperienced mixer. Refining this aspect of your work can be extremely taxing at first, and even has the potential to shake your confidence as a mixer as you iron out your low frequency management skills. Having a tuned and treated room is key, along with having go-to methods of troubleshooting low end complications in order to keep mixes always moving toward completion.
Still, there is no substitute for putting in the time and dedication needed to get your foundation right, and there are plenty of time-tested measures you can take to make the process easier and your mixes more balanced.
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