Kick and bass relationship: tuning, phase and note choice before you reach for EQ

Ask ten producers how to make a kick and a bass sit together and nine will say "sidechain it" or "cut the bass at 60Hz". Both work. Both are also repairs. Most kick and bass fights are decided earlier, by three things the mixer cannot fully fix later: what note the kick is, what notes the bass plays against it, and whether the two waveforms push and pull the speaker in the same direction.

This guide covers those three. It is written to sit next to our low end and bass mixing guide, which handles filtering, EQ carving and saturation, and our sidechain compression guide, which covers ducking in depth. If you fix pitch, note choice and phase first, you will need far less of either.

Why the kick has a note

A kick drum is a short burst of noise (the click) followed by a decaying tone (the body). That tone has a pitch. On an acoustic kick it is usually low and short enough that nobody notices. On a long electronic kick, and especially on an 808 style kick that doubles as the bass, the tail is a clear note that lasts long enough to clash.

If the song is in F and the kick tail rings at a pitch near F sharp, every hit adds a dissonance a semitone away from the root. Listeners rarely name it. They just hear the low end as muddy, or the kick as "not hitting", and the usual reaction is to EQ harder.

Step 1: find the kick's pitch

You need two numbers: the frequency the kick settles on, and the note that frequency belongs to.

1. Solo the kick and put a tuner or a spectrum analyser on it. Ableton Live 12 ships a Tuner device that shows the detected note; most DAWs have an equivalent, and a free plug-in tuner works too.
2. Read the tail, not the attack. The first few milliseconds sweep down from a higher pitch; what matters is where the body settles.
3. If the tuner jumps around, loop just the tail and check the strongest low peak on an analyser instead.

To turn a frequency into a note, use the standard reference. ISO 16 fixes the A above middle C at 440Hz. In equal temperament each semitone up multiplies the frequency by the twelfth root of 2, about 1.0595, so every octave doubles it. Counting semitones from that A gives a handy formula, where n is the number of semitones above it (negative below):

frequency = 440 × 2^(n / 12)

Working down from 440Hz by octaves gives A at 220, 110, 55 and 27.5Hz. The low notes most kicks sit on, roughly 40 to 65Hz, run from about E (41.2Hz) up to about C (65.4Hz).

Step 2: tune the kick to the song

Once you know the kick's note, decide what it should be. Three choices work in practice:

• The root of the key. Safest. The kick reinforces the tonal centre on every hit.
• The fifth. Also consonant, and it can stop a root-note kick from blurring into a bass that sits on the root.
• Whatever note is left over by the bassline. Useful in tracks where the bass moves a lot (see Step 3).

Then retune. In a sampler, transpose the sample by semitones and fine-tune by cents until the tuner reads the target note. If the kick is synthesised, set the oscillator's base pitch directly. Two cautions:

• Transposing a sample also changes its length and attack. Shift more than three or four semitones and the kick may lose its click or ring too long. If so, pick a different kick sample whose natural pitch is nearer the target rather than forcing one.
• A pitch envelope still sweeps from above the note. Tune the settled body, then adjust the sweep by ear for punch.

Step 3: choose bass notes that leave the kick room

Tuning only helps if the bass cooperates. The kick hits the same note every time; the bass moves. Every time the bass lands on a note a semitone or a whole tone from the kick at the same moment, the two beat against each other.

A practical way to work:

1. Mark where the kick lands in each bar.
2. Look at which bass note sounds on each of those hits.
3. If a clash keeps repeating (a semitone or tone away, both in the lowest octave), change one of: the bass note at that moment, the octave the bass plays in, or the kick hit itself.

Moving the bass up an octave on clashing notes is often the cleanest fix, because it takes the bass's fundamental out of the kick's range while the ear still hears the same note. The other classic move is rhythmic: let the bass start just after the kick, or leave a gap where the kick lands. That is the musical version of sidechain ducking.

For 808 style tracks where one sound is both kick and bass, this step merges with Step 2: the 808 changes pitch with the bassline, so the click layer on top is the only thing that stays fixed, and the layering drums guide covers how to keep that click consistent.

Step 4: check the phase between kick and bass

Two low sounds playing at once add up when their waveforms move together and partly cancel when they move in opposite directions. In the bottom octave this matters more than anywhere else, because the waves are long.

The maths is simple. At 50Hz one cycle lasts 1/50 of a second, which is 20ms. If the bass is 10ms late against the kick at that frequency, the two are half a cycle apart: one pushes the speaker out while the other pulls it in. A sample start, a slow attack on a bass synth, or a latency-compensated plug-in can easily add delays of that size.

How to check:

1. Loop a bar where kick and bass hit together. Listen to the combined low end in mono.
2. Flip the polarity of the bass. In Ableton Live, the Utility device has phase-invert switches per channel; most DAWs have a polarity button on the channel strip.
3. Whichever setting gives the fuller, louder low end on the hit is the one to keep. If neither is clearly better, the problem is timing, not polarity.
4. For timing, nudge the bass a millisecond or two at a time, or move the kick sample's start point, and listen for the low end to fill in.

Do this before EQ. Cutting a frequency band to fix what is really a cancellation removes level you could have had for free.

Step 5: only now, EQ and sidechain

With the kick tuned, the notes arranged and the phase sorted, go back to the tools you already know. You will usually find the EQ moves are smaller and the sidechain can be gentler. Our EQ basics guide covers the filter shapes, and the two guides linked at the top cover the rest.

What we think

Most advice on kick and bass treats it as a mixing problem, and it gets taught as a mixing problem because that is where the plug-ins are. We think it is mostly a writing problem. The kick is a note, the bass is a line, and a line that respects the note leaves very little for the mix to repair.

That matters for artists, not just engineers. A producer who tunes the kick and writes the bass around it makes decisions that belong to the song: which note the track leans on, where the low end breathes. A producer who leaves it all to sidechain and a high-pass filter hands those decisions to presets, and the track ends up with the same pumping, carved low end as every other track using the same presets. Ducking is a fine tool. It just should not be the first place your low end gets its character.

There is also a practical reason. Small speakers, earbuds and laptops barely reproduce a 45Hz fundamental. What they do reproduce is the harmonics, and harmonics of a kick and bass that agree on pitch sound clean even on a phone. Harmonics of two notes a semitone apart sound like mud everywhere. Tuning is the cheapest translation fix there is.