The Rhythm Section Pro module approaches the bass as a player would - articulation, feel and mechanics. Here the question is compositional: what is the bassline doing to the harmony?
The answer is: more than any other part. The ear hears the lowest note as the foundation of the chord. Change the bass note and you change the chord, even if nothing above it moves.
The bass defines the chord
Play C-E-G over a C in the bass: C major. Play the same three notes over an A: Am7. Over an F: Fmaj9. The upper notes did not change - the bass reinterpreted them.
This is one of the most powerful tools a producer has. A pad holding one chord for eight bars can sound like a progression if the bass moves underneath it.
Roots, inversions and passing notes
- Root notes state the harmony clearly. When in doubt, the root is right.
- Inversions put the third or fifth in the bass. A bassline that moves C - E - F instead of C - C - F creates a smoother line and a lighter feel.
- Stepwise lines connect chords by step. C - B - A - G under C - G/B - Am - Am/G is one of the most familiar descending basslines in pop, soul and classical music.
- Passing notes fill the space between chord tones on weak beats. They are what turn a list of roots into a line.
Pedal points
A pedal is a bass note that stays the same while the chords above it change. C held under C - F/C - G/C - C builds tension because the chords above keep clashing gently with the unchanging bass, then releases it when the harmony comes back into line.
Pedals are everywhere in electronic music, where one root note can hold an entire breakdown while synths and pads move above it.
Riff and counter-melody
- A bass riff repeats a melodic figure that becomes a hook in its own right. A great riff can carry a song with almost nothing else.
- A counter-melody moves independently of the vocal - rising when the melody falls, moving when the melody holds. The two lines talk to each other.
Contrary motion - bass and melody moving in opposite directions - is one of the oldest and most effective ways to make two parts sound distinct.
Outlining the chord
Arpeggiated basslines - root, third, fifth, octave, in rhythm - outline the harmony note by note. They are common in disco, synth-pop and classical music, and they work especially well with synth basses where each note has a clear attack.
Writing the bass first
Try writing a bassline before any chords exist. Write a strong, rhythmic, melodic line, then ask what chords it implies. Each bass note can support several chords: an A could sit under Am, F, D7 or Fmaj7. The bassline gives you the structure; the chords become a choice of colour above it.
This approach is common in dance music, funk and hip-hop, where the bass is the main event.
Register and range
- Keep most of the line between roughly E1 and G2 for weight and clarity.
- Very low notes (below about 40 Hz) are felt more than heard and disappear on small speakers.
- If the bass goes too high it starts to compete with the chords and vocal.
- In dense arrangements, simpler basslines usually work better.
Do this now
- Hold a C major chord on a pad for eight bars and write a bassline underneath that makes it sound like four different chords.
- Write a descending stepwise bassline from C to G, with a chord above each note.
- Write a bass riff first, with no chords, then choose two different chord progressions that fit under it and compare them.