How to mix kick and bass

The overlap between kick and bass

Most of a kick drum's weight sits somewhere between 40 and 100 Hz. A bass line's lowest notes sit in the same place: the bottom string of a four-string bass guitar is E1 at 41.2 Hz, and A1, the root of a song in A minor, is 55 Hz. When two sounds share a band like that, the louder one hides the quieter one, which is called masking, and down here your ears are poor at telling two sounds apart anyway. What you hear is one thick, blurry thump on every beat.

The second problem is in the waveforms themselves. At these frequencies a single cycle lasts 10 to 25 milliseconds, about as long as the punchy front of a kick, so the two waveforms add together cycle by cycle. Where they push the same way at the same moment, the sum is bigger than either. Where one pushes up while the other pulls down, they partly cancel.

Say the kick peaks at −3 dBFS and the bass at −6 dBFS. As plain amplitudes that's 0.71 and 0.50. If their peaks line up, the sum reaches 1.21, which is +1.7 dBFS and over the top of the scale, so the mix clips or your limiter has to work on every beat. If they're exactly opposite, the sum is 0.21, or −13.7 dBFS, and the kick sounds thin. Which one you get depends on the bass note and where in its cycle the kick lands, so it changes from beat to beat, and that's how a kick can sound fine in bar one and weak in bar three.

The figure uses the kick from the lab and a 55 Hz sine for the bass. The kick's note is falling the whole time, so it never lines up with the bass for long and never cancels it completely. The sum still peaks above 0 dBFS at every phase, and the energy of its first 100 ms swings by about 3 dB as you move the slider. In a real track that swing happens from one beat to the next, and the loudest beats decide how much headroom you have left.

Decide which one owns the sub

Before reaching for a plug-in, decide which of the two carries the lowest octave, roughly 30 to 60 Hz, which people call the sub. Everything else on this page follows from that choice. Skip it and both parts tend to end up boosted in the same place.

In a lot of house and techno the kick gets the punch, centred somewhere around 50 to 100 Hz, and the bass gets the sub but plays mostly between the kicks, so they take turns. In trap and drill the 808 is the bass, a long sine with a pitch, so the kick is short and clicky and sits above it, or it's left out on the beats where the 808 starts a note. In rock and a lot of pop, the kick drum has its weight around 50 to 80 Hz and the bass guitar's tone sits a little higher, around 80 to 250 Hz, with its lowest end filtered or tucked under the kick.

Any of these works. Pick the one that suits the song and commit to it with EQ, so you aren't adding the same low frequencies to both and hoping the mix sorts them out.

Reading the lab

The lab above is a sidechain compressor on the bass, listening to a kick. The kick is a plain sine kick on every beat at 120 BPM, generated in your browser, and the bass is the bass loop from Flow, in A minor at the same tempo. The purple lane at the top of the big screen is the kick. Under it the pale shape is the bass before the compressor, the pink shape is the bass that comes out, and the amber lane at the bottom shows how far the bass is being turned down at each moment. Hover over the screen, or press and drag on a phone, to read the numbers.

The close-up shows half a second, one beat, starting just before a kick, with the attack time shaded and a dashed line where the bass is back within 1 dB of full level. The panel beside it describes your settings from numbers measured on the loop: the deepest duck, how far down the bass still is when the next kick arrives, and how much of the loop it spends ducked.

Press A/B to switch the ducking off. The lab matches the loudness of the two versions, so you're comparing the low end and nothing else. The Trigger fader sets how loud the kick is in what you hear, but the compressor listens to the kick before that fader, so muting it keeps the ducking going. You can also pick a 110 Hz sine as the target, or load your own bass line.

Tune the kick to the song

A kick with any length of tail has a pitch. Many electronic kicks are a sine wave whose pitch drops fast, and the note it settles on is the one you hear in the tail. When that note is a semitone or so away from the bass, the low end sounds muddy in a way EQ won't fix, because the two notes beat against each other.

The kick in the lab starts at about 155 Hz, passes 55 Hz around 70 ms in and ends up near 45 Hz, about halfway between F1 (43.7 Hz) and F♯1 (46.2 Hz). So its tail isn't tuned to the A minor of the bass, and it gets away with that because it fades out quickly. You'd hear the clash on a long 808, where the tail rings for half a second or more.

To find the pitch of a kick, put a spectrum analyser on it and look for the tallest peak in the tail, or play the kick against a sine and move the sine until the beating stops. Then tune it with the sampler's pitch control so the tail lands on the song's root or fifth: for a song in A, that's A1 at 55 Hz, or E1 at 41.2 Hz just below it. If you want a punchier, higher kick, E2 at 82.4 Hz is the fifth an octave up.

EQ: give each one its own band

Once you know who owns the sub, use EQ to make the split clearer. Make small cuts in one part where the other is strong, so you're carving room instead of piling up boosts. A cut of 2 to 4 dB is usually enough.

If the bass owns the sub, find the frequency where the kick's thump is loudest, often 50 to 90 Hz on a punchy kick, and cut the bass there with a medium-width bell. Then turn down the kick's lowest octave with a gentle low shelf or a high-pass around 40 Hz, so its tail doesn't sit on top of the bass's fundamental. If the kick owns the sub, do it the other way round: high-pass or shelf the bass under about 50 Hz and let the kick's tail fill that space.

Both parts usually have a boxy range between 200 and 400 Hz that you can cut a little to stop the low mids building up. Above that they don't fight much. The kick's click, from the beater or the attack of the sample, lives around 2 to 5 kHz, and a small boost there helps it cut through without any more low end. The bass's harmonics, from around 700 Hz up to 2 kHz, are what let you hear its notes on small speakers.

A high-pass at 20 to 30 Hz on both takes out rumble below the lowest note, which you barely hear but which still uses up headroom. The frequency ranges lesson has the bands in more detail, and low cut vs low shelf covers which filter to use where.

Sidechain the bass to the kick

EQ splits them by frequency. A sidechain compressor splits them by time: it sits on the bass, listens to the kick and turns the bass down for the moment each kick plays. For the first 100 ms or so of every beat the kick has the low end to itself, and between kicks the bass is back at full level. The sidechain compression lesson covers how the effect works in general. For kick and bass you want a duck short and shallow enough that nobody notices the bass moving.

How deep

For a clean low end, 3 to 6 dB of ducking is enough. A 6 dB duck halves the bass's level while the kick plays. Use a ratio around 4:1 and bring the threshold down until the duck meter shows that much on each kick. Once the bass is dropping 15 or 20 dB, the duck itself becomes a sound, and you're on the way to pumping.

Attack

Keep the attack fast, anywhere from under 1 ms to about 5 ms. The kick's click and its first few cycles are what needs the room, and a slow attack leaves the bass sitting under them before it gets out of the way.

Release

The release sets how long each gap in the bass lasts, and it needs the most care. You want the bass coming back up as the kick fades, which for a short kick is often 80 to 150 ms and for a longer kick is more.

Too short has its own problem. A 45 Hz note takes 22 ms per cycle, so with a release faster than that the gain moves with each cycle of the kick. The bass gets turned down on every peak of the kick's waveform and recovers in between, and you hear that as a buzz on the bass.

Too long, and the bass hasn't finished coming back when the next kick arrives. One beat at 120 BPM lasts 500 ms (60,000 divided by the tempo), so a release of 400 or 500 ms keeps the bass climbing for most of every beat. That's the pumping sound of a lot of dance music. On pads it's a fine effect; on the bass it takes away weight you wanted.

To set it, mute the kick and listen to the bass on its own. There's a gap on every beat, and each should last about as long as the kick. If the gaps sound longer than the kick, shorten the release; if the bass sounds chopped, lengthen it.

Setting it up in a DAW

Put a compressor with a sidechain input on the bass, then pick the kick as its source, the track the compressor will listen to instead of the bass itself. In Ableton Live, open the Sidechain section of the Compressor and choose the kick under Audio From. In Logic Pro, choose the kick track from the Side Chain menu at the top of the Compressor. In FL Studio, route the kick's mixer track to the bass's mixer track as a sidechain, then select it as the input of Fruity Limiter in compressor mode.

If the kick has reverb or an extra layer you don't want setting off the duck, feed the sidechain from a dry copy of just the kick. A muted copy works fine, because the compressor only needs to hear it.

Volume shaping instead of a compressor

A compressor ducks in response to the kick, so the duck follows the kick's level and timing exactly. A volume shaper draws the dip as a shape that repeats every beat. Xfer LFOTool and Cableguys VolumeShaper both do this, and most DAWs can do it with volume automation or an LFO. A drawn shape stays identical from beat to beat, which helps when the kick's level varies, while a compressor copes better with a kick pattern that isn't regular. Sidechain vs volume shaping compares the two side by side.

Duck only the low end of the bass

A full-range duck turns down the whole bass, including the harmonics that make its notes audible, even though only the low end is in the kick's way. If the gaps are obvious on a bright bass, duck the low band on its own. A multiband compressor with a sidechain input can turn down just the band below 100 or 150 Hz on each kick and leave the rest of the bass alone. A dynamic EQ band does the same more precisely: put a bell on the bass at the kick's thump frequency and let the kick, through the sidechain, push it down. FabFilter Pro-Q 3 and Pro-Q 4 can do this with an external sidechain, and Wavesfactory Trackspacer is a plug-in made for this kind of frequency-by-frequency ducking.

Phase and polarity between kick and bass

The figure near the top showed that the sum of the kick and bass depends on how their waveforms line up. You can't control that for every note, but you can check the overall relationship. Play them together, flip the polarity of the bass and listen for which version has more low end; Ableton's Utility and Logic's Gain plug-in both have a switch for it. With a sampled or recorded bass you can also slide it a few milliseconds earlier or later and listen for the same thing, though push it too far and the groove starts to drag.

Check the low end in mono as well. If a bass has stereo chorus or width below about 100 Hz, its left and right sides can partly cancel in mono, so it gets thinner on a mono club system or a phone. Keep the kick and the low end of the bass in mono and put any width higher up. The mono compatibility lesson shows how to check.

Arrange them so they take turns

The cleanest fix happens before mixing, by writing parts that don't land on top of each other. A bass on the off-beat, between the kicks, has the low end to itself for every other eighth note, which is a big part of the sound of a lot of house and trance. Shorter bass notes that stop before the next kick do the same thing more gently. Where the 808 is the bass, producers often leave the kick out wherever the 808 starts a new note, or use a kick that's mostly click.

If the arrangement already gives them separate moments, you might not need a sidechain at all; the short duck is for the places where the bass has to sit on the kick.

Hearing the bass on small speakers

Once the kick and bass are separated, check them on something small. Phone speakers and most laptop speakers reproduce almost nothing at 50 Hz, so a bass that's all sub disappears there and leaves only the kick's click. Saturation helps by adding harmonics at two, three, four and more times the note's frequency. The higher ones land where those speakers work, and your ears fill in the low note from the pattern of its harmonics. Saturate a parallel copy of the bass and high-pass the copy above about 150 Hz, so the sub itself stays clean. The saturation lesson covers the different types.

How to mix kick and bass, step by step

1. Pick the sub ownerDecide whether the kick or the bass carries 30 to 60 Hz in this song, and turn the other one down there.
2. Tune the kickIf it has a long tail, find the pitch of the tail and move it to the song's root or fifth.
3. Set the balanceBring the kick and bass up together at a moderate level, then turn it down and check the kick still comes through.
4. Carve with EQCut the bass 2 to 4 dB where the kick thumps and high-pass both around 20 to 30 Hz. Clear a little 200 to 400 Hz if the low mids build up.
5. Add a short duckSidechain the bass to the kick with a fast attack and aim for 3 to 6 dB of gain reduction. Then mute the kick and set the release so each gap in the bass is as long as the kick.
6. Check polarity and monoFlip the bass's polarity to hear which way has more low end, then listen to the pair in mono.
7. Try small speakersPlay it on a phone or laptop, and saturate the bass if its notes vanish.

Common kick and bass mistakes

Boosting the same band on both

Adding 4 dB at 60 Hz to the kick and another 4 dB at 60 Hz to the bass adds more to the band they already share, so neither stands out. If one needs more weight, take some away from the other at the same frequency.

Mixing the low end in solo

A kick soloed with a big low shelf sounds great on its own and then swamps the bass in the mix. Make your low-end decisions with both playing, and with the rest of the track when you can.

Trusting a room you don't know

Untreated rooms have big peaks and dips below 200 Hz, so you might cut a bass note that only sounds loud where you sit. Compare against a reference track in the same style, check on headphones as well as speakers, and look at a spectrum analyser for the lowest octave.

Ducking the bass away

A sidechain set for pumping on a pad is too much for the bass. If the bass sounds weak with the kick muted, raise the threshold or shorten the release until the gaps are only as long as the kick.

Train your ears

The quiz under the lab hides the settings and matches the levels. The first four rounds ask whether the sidechain on the bass is on or off, and the last four whether the release is fast or slow. A short duck is easy to miss, so listen to the very start of each beat, where the bass either gets out of the way or doesn't.

Questions people ask

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