Music Craft4 min read

Mixing Bass: Sub, Mid-Bass, and Making It Translate on Small Speakers

Bass has two jobs and two frequency ranges. Here is how to split sub and mid-bass, use saturation so bass survives on phone speakers, and keep everything below 120 Hz in mono.

Bass has two separate jobs and they live in two separate frequency ranges. The sub, below about 100 Hz, carries weight you feel. The mid-bass, roughly 200 Hz to 1 kHz, carries the notes you actually hear on small speakers. A bass mixed for only one of those ranges fails on half the world's playback systems.

Split the bass into two parts

The most reliable technique is to treat sub and mid-bass separately, either by splitting one track into two bands or by layering two sources.

  • Sub layer: low-passed at 100–120 Hz, mono, minimal processing, often a sine wave. Weight only.
  • Mid layer: high-passed at 100–120 Hz, this is where saturation, character and note definition go.

Splitting lets you compress the sub hard for consistent weight while leaving the mid-bass dynamic and expressive — two goals that are impossible to serve with one processor.

Saturation, and why it is not optional

Harmonic saturation generates overtones at whole-number multiples of the input frequency. A 50 Hz note driven into saturation produces content at 100 Hz, 150 Hz, 200 Hz and upward. Because of the missing fundamental effect, the ear infers a 50 Hz note from that harmonic series even on a speaker that cannot reproduce 50 Hz at all.

Practical approach: send the mid-bass layer to a saturator (tube, tape or a soft-clipper), drive it until you can hear the note clearly on a phone speaker, then check it has not become buzzy on monitors. Distorting the sub layer itself is usually a mistake — it muddies the low end. Saturate the mids, keep the sub clean.

Frequency reference

RangeWhat lives thereCommon move
Below 30 HzInaudible rumbleHigh-pass it out
30–60 HzSub weightKeep mono, control with compression
60–120 HzFundamental for most bass notesWhere kick collisions happen
120–250 HzWarmth, can get boomyCut 2–3 dB if the mix feels thick
250–700 HzBody and note definitionWhere the bass becomes audible on laptops
700 Hz–2 kHzAttack, pick noise, growlBoost for presence in a dense mix
Above 3 kHzString and fret noiseUsually low-pass, unless you want grit

Compression

Bass benefits from more compression than most instruments because level consistency matters more than dynamics — an inconsistent bass makes the whole mix feel unsteady.

Start with ratio 4:1, attack 10–30 ms so the note attack survives, release timed so the compressor recovers between notes (roughly 100–200 ms at typical tempos), and 4–8 dB of gain reduction on the loudest notes. For a synth bass with an already flat envelope, less is needed.

If specific notes jump out, the cause is usually room resonance or a resonant note on the instrument, not the compressor. Fix it with clip gain on those notes or a narrow dynamic EQ cut.

Mono below 120 Hz

Use a utility or mid/side plugin to force everything below roughly 120 Hz to mono. Reasons:

  • Phase differences between left and right in the sub range cause cancellation in mono playback — club systems, phone speakers, many Bluetooth speakers.
  • Stereo sub content uses substantially more headroom for no perceived width.
  • Vinyl cutting requires mono low end.

Stereo width above 200 Hz on a bass is fine. Wide chorus or unison on the mid layer while the sub stays mono is a standard trick.

Fitting the bass around the kick

Decide which element owns each part of the low end. If the kick owns 60 Hz, notch 60 Hz in the bass by 2–3 dB and let the bass own 90–110 Hz. Add 3–6 dB of sidechain ducking on the bass triggered by the kick, or duck only the sub band with a dynamic EQ so the mid-bass stays continuously audible.

The translation check

Play the mix on a phone speaker. If the bassline is inaudible, add saturation, not level. Then check on headphones with real low-end extension — if the sub is now overwhelming, the sub layer is too loud and the saturation was doing the work all along. That contradiction is normal, and resolving it is the whole job.

Related reading: writing basslines, sidechain compression explained, and gain staging explained.

Frequently asked questions

Why does my bass disappear on phone speakers?

Phone and laptop speakers cannot reproduce anything below roughly 200 Hz. If all your bass energy is sub content, there is nothing left to play. Adding harmonic saturation creates overtones at 200 Hz and above, so the ear reconstructs the missing fundamental.

Should bass be in mono?

Everything below about 120 Hz should be mono or very close to it. Stereo sub content cancels unpredictably when summed to mono, wastes headroom, and causes problems on vinyl and club systems. Width above 200 Hz is fine and often useful.

How loud should the bass be in a mix?

In most modern genres the bass and kick together sit within a few dB of the loudest elements, with the bass roughly level with or slightly below the kick. Rather than a fixed number, check on several playback systems and against a reference track in the same genre.

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