The low-end relationship between bass guitar and kick drum is one of the most fundamentally important relationships in a mix. A rhythm section that’s perfectly in step with each other and alsowell mixed can take a track (and a band) to the next level, while a sloppy and indistinct low-end can drag a song down no matter how good the playing is.
Together, the bass and kick should create a feel that’s powerful and moving without crowding either instrument or forcing one out of the way of the other.
When EQ’ing the combination of bass and kick, a conscious decision needs to be made about which one gets to win the low-end battle. Is the bass rounding out the bottom end with a rich tone and some serious low notes, while the kick drum is more snappy and clicky? Or, does the kick drum need the attention for a deep, sustained sound?
The choice is a stylistic one, and it’s really up to the needs of the mix.
Whichever instrument you decide will drive the low-end, wrap the other instrument around it with its EQ. For example, if the kick is emphasized at 80Hz, make sure the bass is not also emphasized at 80Hz but give it some emphasis at 40Hz and 120Hz.
A good mid-range area to boost is between 2–5kHz, which will help a bass poke through a dense mix. This 2–5kHz area is where the upper harmonics that more easily identify the bass tone and pitch are located.
Some harmonic distortion can also help enhance frequencies in this area. Adding tube-style distortions will thicken up the low end of a bass guitar, while adding tape-style distortions will introduce harmonic distortion that will be more noticeable in the mid- to higher- ends. Try tape-style distortion for brightening up the 2–5kHz area.
As you work to find the right EQ and distortion, continue bypassing and un-bypassing your settings to make sure you’re really able to hear—not just see—the changes you make. We’ve gotten so used to working on computers during our music production that it’s easy to begin to judge our mixes based on what waveforms and changes in audio look like.
As a result, our eyes can often fool us into thinking we hear the change occurring. It’s important to listen carefully and be sure to make choices based on the true audio signal. Try turning your computer monitors off completely from time to time, to make sure you're hearing what you think you’re hearing.
Bass compression can vary depending on how the instrument is played. If the song has an upright bass, subtle to moderate compression with a moderate attack and release time is best. If an electric bass is played with a pick or “funk style” with a thumb, faster attack and release times may be necessary to tame the transients.
For fingerstyle electric, attack and release times can go back to moderate. These ratios often vary between 3:1 to 6:1 but can go as high as 10:1. It’s important to note how much gain reduction is occurring. Subtle gain reduction would result in the peaks being attenuated by approximately 2-3dB, where moderate reduction would be close to 6db. Make sure to apply makeup gain, or auto-gain, if your tool has such a feature. Without it, the bass will be getting smoother, but also quieter, which can cause it to get lost in a mix.
Another useful tool for separating kick and bass is side-chain compression. This form of compression uses one instrument’s level over a threshold to activate the gain reduction (compression) on another instrument.
For example, inserting a compressor on a bass track that reacts to the kick drum will compress the bass every time the kick drum is hit. This method will tame the bass track and duck it out of the way each time the kick is hit, while still maintaining its overall level in the mix.
Unlike drums, bass is both a heavily rhythmic and harmonic instrument. While every kick drum hit is largely the same tone, the fundamental note on a bass changes for every note the bass player strikes—which makes nailing the low-end on bass a lot like trying to hit a moving target. Sometimes, the harder you work at it, the more off target you get. If the bass part has a lot of movement, you may have to make further adjustments using automation.
Don’t be discouraged if it takes a while to get your low end to really shine—bass can be the most difficult instrument to manage in a mix. If you get stuck, try pulling up some of your favorite recordings and listen closely to how the bass sits in comparison to the kick.
With a little practice and focus, you’ll be able to craft just the right sound for your rhythm section.