Low end and bass mixing: getting kick and bass to share the bottom of the mix

Ask anyone who mixes for a living where home mixes fall apart and most will point at the bottom octave or two. The low end is where the loudest energy in a track lives, where small monitors and untreated rooms tell you the least, and where two instruments, the kick and the bass, almost always want the same space. Get it right and everything above it sounds bigger. Get it wrong and the whole mix sounds either thin or muddy, and turning it up just makes it distort sooner.

This guide is a practical order of work, not a list of magic frequencies. We lean on Mike Senior's Mixing Bass feature in Sound On Sound, which is still one of the clearest write-ups of the problem, and on Ableton's EQ Eight documentation for the tool details. Any DAW's stock EQ and compressor will do the same jobs. If EQ is new to you, read our EQ basics first.

Why the low end is the hard part

Senior describes the clash between kick and bass as "the most critical sub-100Hz conflict in modern mixes", and the reason is headroom as much as clarity. Those two sources usually account for most of the level hitting your mix bus. When they peak at the same moment, they eat the room the rest of the mix needed, so the track ends up quieter, or the limiter works harder and squashes everything.

There is a second problem: you often cannot hear what is happening. Small speakers roll off the deepest notes, and rooms build up some bass frequencies while cancelling others depending on where you sit. So the low end is both the most important region and the one you can trust your ears least on. Everything below is built around that.

Step 1: decide who owns the bottom

Before touching a plug-in, decide which instrument carries the lowest fundamental in each section. In a lot of hip-hop and electronic music it is a long 808 or sub bass, and the kick is short and clicky above it. In a lot of rock and pop it is the kick's thump, and the bass guitar sits a little higher with its growl and harmonics doing the work. Both approaches are fine. What fails is two instruments each trying to be the deepest thing in the room at the same time.

This is an arrangement choice first. If the bass plays long notes right on every kick, you will fight it all mix long. Shortening the bass, moving a note off the beat, or letting the kick drop out where the bass has a big sustained note solves more than EQ ever will. Our arrangement basics guide covers that kind of decision.

Step 2: tune the kick

This is the most underused trick in the toolbox. Senior suggests adjusting the pitch of the kick sample so its low-frequency peaks fall into gaps in the bass's spectrum. Because a bass line moves through notes while a kick's pitch stays fixed, a kick that sits on, or near, the root of the song's key tends to sound like it belongs. The article adds that this can save EQ work and reduce phase cancellation between the two.

To do it, solo the kick with a spectrum analyser and find its strongest low peak, then transpose the sample a few semitones up or down while the bass plays and listen for the setting where both feel solid together rather than one swallowing the other.

Step 3: filter what does not belong

Plenty of tracks carry low-frequency content nobody intended: rumble on a vocal mic, low hum on a synth pad, room noise on an acoustic guitar. Individually it is quiet. Summed across twenty tracks it becomes the "mud" people complain about.

Put a low cut (high-pass) filter on tracks that have no business down there and raise it until you hear the instrument itself start to thin, then back it off a touch. In Ableton's EQ Eight the relevant modes are a "48 or 12 dB/octave Low cut", and the manual notes the low cut has no gain control. The steep setting is a cleaner tool for removing rumble; the gentle one is better when you want to lean on an instrument's weight rather than delete it.

Do this by ear, in the context of the full mix, not soloed. Soloed, every track sounds better with its low end intact.

Step 4: carve with EQ, gently

Once ownership is clear, use EQ to support it. The usual move is complementary: a small boost on the kick where its punch lives and a small cut on the bass in the same place, and the reverse where the bass needs to be heard. Narrow, modest cuts beat wide, deep ones; you are making room, not removing an instrument.

Often the biggest gain for the bass is not in the low end at all. Its audibility on phone speakers and laptops comes from its upper harmonics, the pluck and growl a few hundred hertz and above. If the bass vanishes on small speakers, that is where to look.

Step 5: duck the bass when the kick hits

If the two still collide on the downbeats, let the kick briefly turn the bass down. Put a compressor on the bass and key its sidechain from the kick. Our sidechain compression guide covers the routing in detail.

The important thing here is restraint. Senior notes that "you can rarely push the ducking further than about 2-3dB per hit without the bass line beginning to sound odd". That is the transparent version, for headroom and clarity. The audible pumping effect in dance music is a different, deliberate creative choice.

Step 6: add harmonics so the bass translates

A clean sine sub is almost invisible on small speakers because there is no energy up where those speakers work. A little saturation on the bass generates upper harmonics that the ear reads as the same note, so the line stays audible on a phone. Use a parallel blend or a low mix setting so the clean low end stays intact. Our saturation and distortion guide covers the types.

Checking low end you cannot hear

Because rooms and small monitors lie about bass, check it in several ways:

• Reference tracks. Load two or three released songs in your genre at matched loudness and compare the balance of kick, bass and everything else. Our guide to reference tracks shows the setup.
• A spectrum analyser. It will not tell you if something sounds good, but it will show you a sub peak your speakers never revealed.
• Headphones. Good closed or open-back headphones skip the room problem entirely for low-end decisions; see our headphone mixing guide.
• Mono. Switch the mix to mono now and then. Low end that relies on stereo width can shrink or cancel on club systems and phone speakers, so many engineers keep the deepest part of the bass centred.
• Other systems. Car, earbuds, laptop. If the bass disappears on the small ones, revisit step 6; if it booms on the big ones, revisit steps 3 and 4.

What we think

The usual advice frames low-end mixing as an EQ problem and hands beginners a list of frequencies to cut. We think that gets the order backwards. Most of the fix happens before an EQ is opened: deciding which instrument owns the bottom, tuning the kick, and arranging so the two parts are not always stacked on the same beat. That matters because those choices are the only ones that work on every playback system. EQ and saturation settings that sound great on your speakers can fall apart on someone else's, but a kick and a bass that take turns sound clear everywhere. If you take one habit from this guide, make it this: when the low end is a mess, mute the bass and ask whether the part itself needs changing before you reach for a plug-in.