Bass lines in pop, rock, funk and disco

Definition

The bass line connects drums and harmony: it supplies the root of the chords (and therefore defines inversions and function), and together with the kick it builds the groove. In pop you write it with three questions in mind: which note (root, fifth, passing tone), when (relative to the kick) and how long (staccato or legato).

Note choices

Root: safe, makes the chord clear. Indispensable in genres where the bass is a sub (EDM, trap).
Fifth and octave: movement without changing harmony (country, rock and roll: alternating 1–5).
Third in the bass: creates inversions (C/E) and smoother descending lines.
Passing tones: diatonic or chromatic between one chord and the next, on the fourth beat or the last eighth note.
Pedal: the same note under different chords (C under C, F/C, G/C) creates tension.

Main styles

Pop/rock in eighths (pumping): repeated root in eighth notes, often with a pick. Gives continuous energy. Example: U2 — With or Without You (1987), bass in eighth notes on a few degrees.
Motown: James Jamerson, with the Funk Brothers, invented a melodic language with chromaticism, ghost notes, anticipations and use of the middle register. Example: Marvin Gaye — What's Going On (1971).
Funk: the bass is percussive. You think in sixteenth notes: a strong accent on beat 1 (“the one,” in the language of James Brown and Bootsy Collins), ghost notes (dead notes) between the accents, octaves and slap (Larry Graham, Sly and the Family Stone, thumb-pop technique).
Disco: alternating octaves in eighth notes (C2–C3–C2–C3) over the four-on-the-floor kick; the high note falls on the “and”s (offbeat eighths). Example: Chic — Good Times (1979, Bernard Edwards), Bee Gees.
Reggae: the bass is the main melody, very low register, wide spaces, often with beat 1 empty (one drop).
Synth-pop: sequenced arpeggios in sixteenth or eighth notes, very precise (Depeche Mode, New Order).

Relationship with the kick

Lock: the bass plays with the kick on the same sixteenth notes; gives impact (rock, pop).
Alternation: the bass plays in the gaps of the kick (kick on 1, bass on 1-and and on 2-and); gives groove (funk, house).
Length: if the kick has a long tail (below 60 Hz), the bass should be shortened or sidechained by 2–4 dB.

Rhythm of the line (in sixteenth notes, one bar)

Pumping pop: x.x.x.x.x.x.x.x.
Disco octaves: low on the beats, high on the “and”s.
Funk: x..x..x.x.x...x. with ghost notes between the accents.
House: offbeat bass, ..x...x...x...x. (on the “and” of every beat), leaves the kick alone on the beat.

Example in A minor, loop Am–F–C–G

Am bar: A1 on beat 1, A2 on 2-and, E2 on 3, G1 on 4-and (passing tone descending toward F).
F bar: F1 on beat 1, F2 on 2-and, C2 on 3, B1 on 4-and (rising by semitone toward C).
C bar: C2 on beat 1, C3 on 2-and, G1 on 3, A1 on 4-and (descending by step toward G1).
G bar: G1 on beat 1, G2 on 2-and, D2 on 3, G#1 on 4-and (chromatic note rising toward A).

The rule: the last note of the bar is an approach (by step or by semitone) to the root of the next chord.

Register and frequencies

4-string electric bass: E1 (41.2 Hz) – about G4. Most pop lines sit between E1 and E3 (fundamentals 41–165 Hz). Notes below A1 (55 Hz) are only audible on large systems: this is why saturation or a layer in the low-mids (100–800 Hz) is added.

Common mistakes

Bass playing above G2 for long stretches during the vocal: it occupies the bass zone of the male voice.
Passing tones on the strong beat that contradict the chord.
Long notes overlapping a long kick: mud between 40 and 100 Hz.

Practical exercise

Write four versions of the same line over the Am–F–C–G loop: pumping eighths, disco octaves, funk with ghost notes, offbeat house. Compare them with the same drums and notice how the perceived genre changes.

Arranging for the rhythm section, Walking bass, 808 lines, Writing drum parts, Groove, swing and microtiming.