Your mix sounds fine on headphones and falls apart in the car. The vocal is clear, the drums snap, and yet the whole thing feels heavy and vague, as though someone parked a duvet over the bottom two octaves. That is almost never a reverb problem and it is almost never a compression problem. It is the kick and the bass standing in the same doorway, and no amount of work on anything else will fix it.
This guide is about the bottom two octaves and the two instruments that fight over them. You will get the frequency anatomy of what actually lives down there, a way to decide which instrument owns which band, the EQ moves that separate them (in the correct direction, which is where most advice on this goes wrong), when to collapse the bottom to mono, and how to check work you probably cannot hear in your room. Sidechain ducking gets a section too, but it belongs fourth on this list, not first.
WHERE KICK AND BASS COLLIDE
- 30–60 Hz60–100 Hz100–200 Hz200–400 Hz400 Hz+
- KickThumpPunchBodyBox
- BassSubNotesWarmthBodyGrowl
- ContestedBothBothBoth
What Actually Lives Below 250 Hz
Before you move a single filter, it helps to know what you are moving. The bottom of a mix is not one undifferentiated rumble. It is two instruments with distinct anatomies that happen to share an address.
A kick drum has three separate jobs spread across the spectrum. The thump, the part you feel in your chest, sits roughly between 40 and 80 Hz, and in modern pop and hip-hop the peak usually lands between 50 and 65 Hz. The body, the woody tone of the shell, runs from about 80 to 200 Hz. The click, the sound of the beater striking the head, is nowhere near the low end at all: it lives around 2.5 to 5 kHz. That last one matters more than people expect, because it is the only part of a kick a laptop or phone speaker can reproduce.
A bass guitar is built differently. Its fundamental is genuinely low: the open low E on a four-string bass is 41.2 Hz, and the low B on a five-string is 30.9 Hz. Above that sits warmth and fullness from roughly 100 to 400 Hz, and then note definition and growl from about 700 Hz to 2 kHz. A synth bass follows the same shape but you control it, which turns out to be an advantage.
Put the two together and the overlap is not a single band. There are two arguments. The loud one is at 60 to 100 Hz, where the kick's thump and the bass's fundamental are both trying to be the lowest thing in the room. The quiet one is at 200 to 400 Hz, where the kick's body meets the bass's warmth, and this is the one that actually produces the sound people describe as muddy. Most people attack the first and never notice the second. You can see every one of these ranges laid out side by side on our Frequency Chart, which now has a collision view that highlights the overlap between any two sources for you.
Decide Which One Owns the Bottom
Here is the decision that makes every other move on this page easy, and it is the one most home producers skip: only one instrument can own the sub. Not both. Not a compromise. You pick.
This is not a matter of taste so much as physics and arrangement. Two sources putting energy into the same narrow band at the same moment sum, and what sums in the low end is level, not clarity. Giving both the bottom octave does not produce twice the weight; it produces a smeared, louder, less defined version of one of them.
Genre gives you a strong default. In hip-hop, trap, house and most electronic music, the kick owns the sub and the bass sits above it, typically high-passed somewhere between 40 and 60 Hz. The 808 is the exception that proves the rule, because an 808 is both the kick and the bass, which is precisely why it works. In rock, funk, soul and most live-band music, the bass owns the fundamental and the kick takes punch around 80 to 100 Hz plus its beater click up top.
If the genre default does not settle it, let the arrangement decide. Mute the bass and play the section: does the track still have weight and motion? Now put the bass back and mute the kick: same question. Whichever one leaves a bigger hole is the one carrying the low end, and that is the one that should own it. Note that this is a listening test in context, not a solo test. The relationship between these two instruments does not exist in solo, so it cannot be judged there.
Carve With EQ, in the Right Direction
Once you know who owns what, EQ is bookkeeping. But the direction of the filter has to be stated plainly, because getting it backwards is the single most common error in low-end advice: a high-pass filter removes energy below its corner frequency and lets the highs through, and a low-pass filter removes energy above it. If a tutorial tells you to high-pass a kick at 150 Hz, it is telling you to delete the kick.
The move itself is a pair: one cut on the instrument that does not own the band, and at most a small boost on the one that does. Cut more than you boost, because a cut creates room without adding level, while a boost adds level and eats the headroom you will want later.
| Decision | On the kick | On the bass |
|---|---|---|
| Kick owns the sub (hip-hop, house, trap) | Leave the bottom alone. Small boost of 1 to 2 dB at its peak, around 50 to 65 Hz. | High-pass at 40 to 60 Hz, 12 dB per octave. Narrow cut of 2 to 3 dB at the kick's peak, Q around 2. |
| Bass owns the fundamental (rock, funk, soul) | High-pass at 40 to 50 Hz. Cut 2 to 3 dB at the bass's fundamental. Boost 1 to 2 dB at 80 to 100 Hz for punch. | Leave the bottom alone. |
| Both sound muddy (either case) | Broad cut of 1.5 to 3 dB somewhere in 200 to 400 Hz, on whichever instrument is less important to the groove. Wide Q, roughly 1. This is the fix people never make. | |
Find the kick's actual peak before you cut the bass at it, rather than assuming 60 Hz. Put an analyzer on the kick, play the loudest hit in the track, and read where the energy piles up. Kicks vary by 20 Hz or more between samples, and a narrow cut placed at the wrong frequency removes bass you wanted while leaving the collision exactly where it was.
One more caution about habits. High-passing every channel at 100 Hz to "clean up the mix" is a widely repeated piece of advice and it costs you more than it gives. The low mids of electric guitars, keys and even vocals carry real weight, and stripping all of it leaves a mix that is technically clean and emotionally thin. High-pass where a track genuinely has nothing useful, not as a reflex. If you want the longer version of how to place these moves, our guide on how to EQ covers filter types, Q and the sweep technique in detail.
Put the Bottom in Mono
Below roughly 100 to 150 Hz, stereo information buys you almost nothing and costs you a lot. There are three reasons, and all three are worth understanding rather than taking on faith.
The first is that directional hearing barely works down there. Your ears locate sound partly by the tiny difference in arrival time between them, and that cue depends on the wavelength being short compared to the width of your head. A 60 Hz wave is about 5.7 meters long. You are not going to hear which side of the room it came from, so panning it achieves nothing you can perceive.
The second is that it can actively hurt. Low-frequency content spread across the stereo field can end up partly out of phase, and when something sums those channels to mono the out-of-phase portion cancels. Plenty of playback is mono or close to it: a phone speaker, a single Bluetooth speaker, many club and PA systems. A bass that sounded huge in your headphones can lose most of its level the moment it is summed.
The third is practical: if the track is ever cut to vinyl, heavily stereo low end is a genuine problem for the cutting lathe, which is why mastering engineers collapse it as a matter of course.
The fix is either an elliptical filter or a mono-maker plugin set somewhere around 100 to 150 Hz, or simply making sure your kick and bass are centered and that any chorus, widener or stereo reverb on the bass is band-limited so it only affects the upper harmonics. Collapse the bottom, not the whole mix. Our guide to panning instruments covers where the rest of the arrangement should sit once the bottom is anchored.
Get the Levels Right Before You Reach for a Plugin
A surprising share of kick-and-bass problems are level problems wearing an EQ costume. Before any filter goes on either channel, get the two balanced against each other with nothing but the faders: set the kick where you want it, then bring the bass up until the pair feels even and the groove locks.
Watch what happens on the master meter when they land together. Two signals playing at once sum to more than either alone, and how much more depends on how correlated they are: two identical, perfectly aligned signals at the same level sum to about 6 dB above one of them, while two unrelated signals sum to about 3 dB. A kick and a bass note on the same downbeat sit somewhere in between, which is why the meter jumps on beat one and why the mix bus compressor grabs there. If you want to work out level sums and gain changes precisely, the dB Calculator does the arithmetic for you.
Leave yourself headroom while you do it. Mixing into a master bus that is already pinned near zero forces every later decision to be a compromise, and the fix is trivial: pull everything down. Our article on gain staging walks through the levels from input to master, and how loud your master should be explains why a quiet mix costs you nothing on streaming.
One more thing about level, and it is about your ears rather than your meters. Human hearing is less sensitive to low frequencies at low listening volumes, so the same mix genuinely sounds bass-light at whisper level and enormous when loud. Balance your low end at a consistent, moderate volume, then check it quiet and check it loud. If you only ever set the bass late at night at a volume that will not wake anyone, you will systematically over-bass every mix you make.
When Ducking Is the Right Answer
Sidechain compression puts a compressor on the bass and keys it from the kick, so that every time the kick hits, the bass drops out of the way and comes back. It is a genuinely useful tool and it is the fourth one you should reach for, not the first.
It is the right call in dense electronic music where the kick has to punch through on every beat and the bass is a sustained, continuous part. There is simply no room for both at once, and ducking manufactures the room rhythmically. The pumping it creates is often the point rather than a side effect.
It is the wrong call in sparse arrangements and in anything with a live feel, where the bass is doing rhythmic work of its own and a compressor chopping at it fights the performance. It is also the wrong call as a first move in any genre, for a specific reason: ducking solves overlap in time. If your kick and bass are fighting because they occupy the same frequency band, ducking hides that for a few dozen milliseconds after each hit and leaves it untouched everywhere else. Separate them in frequency first, then decide whether you still need to duck. Our full guide to sidechain compression covers routing it in each DAW, setting attack and release, and the six places it helps beyond kick and bass.
How to Check Low End You Cannot Hear
This is the part that makes low end genuinely harder than the rest of mixing: in a normal room, on normal speakers, you cannot trust what you hear below about 300 Hz.
Small rooms produce room modes, standing waves at frequencies related to the room's dimensions, and they create peaks and nulls that can run to many decibels. They are position dependent, so moving your head a foot changes what you hear. A null at 70 Hz will have you boosting a bass that is already too loud everywhere else in the world. Most nearfield monitors compound it by not reproducing much below 50 Hz in the first place, which is a real argument for treating the room and for knowing your speakers' actual limits. Our guide to studio monitors covers what each size can and cannot do down low.
So you verify rather than trust. Four checks, in order of usefulness:
- A spectrum analyzer. Not to mix by eye, but to confirm that the peak you think is at 60 Hz is actually at 60 Hz, and to catch sub energy that your speakers are not reproducing at all. Our article on reading a spectrum analyzer covers what the display is telling you.
- Reference tracks. Pick two commercial records in your genre, level-match them to your mix, and switch. Level-matching is not optional: louder always sounds better, so an unmatched comparison tells you nothing.
- Other systems. A phone speaker, earbuds, a car. The phone is the most informative of the three precisely because it reproduces almost nothing below 500 Hz. If the groove still reads there, your bass has enough harmonic content in the mids to survive.
- A mono check. One button, and it catches phase problems in the low end that are invisible in stereo.
That phone-speaker point deserves its own note, because it explains something otherwise mysterious. The ear reconstructs a pitch from the pattern of its harmonics even when the fundamental itself is missing, which is how a bass line is still recognizably a bass line on a device that cannot produce a single one of its fundamental frequencies. The practical consequence is that a bass part needs harmonic content in the mids to travel, and adding it is what saturation and distortion on a bass channel are really for. A bass with a huge fundamental and nothing above 300 Hz will disappear on half the devices your listeners own. If you are mixing on headphones, our studio headphones guide is worth a read on which ones represent the low end honestly.
A Working Order
Put together, the whole process is five steps in a fixed order, and the order is doing real work. Each step changes what the next one is judging, so running them out of sequence means redoing them.
THE ORDER TO FIX IT IN
- CHOOSE who owns the sub
- LEVEL balance before plugins
- CARVE one cut, one small boost
- MONO bottom to the center
- CHECK analyzer, phone, car
Choose first, because every later decision depends on it. Level second, because EQ decisions made against a bad balance get undone. Carve third, with the cut doing most of the work. Mono fourth. Check last, and be willing to go back to step two when the car tells you something the room did not.
Five Mistakes That Keep the Mud
High-passing the kick too high. A high-pass filter removes what is below it. Set at 100 Hz or above on a kick, it deletes the thump and leaves you with a click, and then you boost the low end back with a shelf and wonder why it sounds wrong.
Boosting both instruments to fix the problem. If the kick sounds weak against the bass, the instinct is to boost the kick. Now both are loud in the same band and neither is clear, and the master bus is closer to clipping. Cut the one that does not own the band instead.
Reaching for sidechain first. It is the most satisfying tool here, which is exactly why it gets used to paper over a frequency problem that a 3 dB cut would have solved permanently.
Mixing the low end quietly, at night, always. Your ears are less sensitive down there at low volume, so you will keep adding bass that is not needed. Check at a moderate level at least once.
Judging the relationship in solo. Kick and bass have no relationship in solo. Both will sound great on their own and terrible together, which is the entire problem. Every decision on this page is made with the section playing.
Start with the decision rather than the plugin: work out which of the two owns the bottom of your track, and the rest of it follows. When you are ready to see exactly where your parts overlap, open the Frequency Chart and put your kick and your bass side by side in the collision view. It will show you the contested bands in seconds, which is quicker than sweeping for them and considerably more reliable than trusting a bedroom room below 300 Hz.
Frequently Asked Questions
Should the kick or the bass be louder?
Neither by rule, but only one of them can own the sub. In hip-hop, trap and house the kick usually owns it and the bass is high-passed above it. In rock, funk and soul the bass owns the fundamental and the kick takes punch around 80 to 100 Hz. Pick one, then set the levels so the pair feels even in context rather than chasing a target number on either channel.
Where should I high-pass the bass?
Between 40 and 60 Hz, at 12 dB per octave, and only when the kick owns the sub. Remember that a high-pass filter removes everything below its corner, so setting it much higher than 60 Hz strips the fundamental of a four-string bass, whose open low E is 41.2 Hz.
Why does my mix sound muddy even after I fixed the sub?
Because the second collision is at 200 to 400 Hz, where the kick's body meets the bass's warmth, and that band is the usual source of mud. A broad cut of 1.5 to 3 dB with a wide Q on whichever instrument matters less to the groove usually clears it.
Do I need sidechain compression on the bass?
Only if the kick and bass genuinely overlap in time after you have separated them in frequency. Ducking solves a timing conflict, not a frequency conflict, so in sparse or live-feel arrangements it often does more harm than good. In dense electronic music with a sustained bass it is close to essential.
How do I mix low end without a subwoofer or a treated room?
Verify instead of trusting. Use a spectrum analyzer to confirm where the energy actually is, compare against two level-matched reference tracks in your genre, and listen on a phone speaker and in a car. A phone reproduces almost nothing below 500 Hz, so if the groove still reads there, your bass has enough harmonic content in the mids to travel.