Bass lines

The bass is the lowest part of a song. It does two jobs at once: it gives the beat weight (you feel it as much as hear it), and it tells your ear which chord the music is on, by playing that chord’s lowest note. A good bass line locks to the kick drum and moves with the chords.

Low notes

Bass notes live in octaves 1 and 2. Compare:

blank("house");
tempo(120);
track("high", note("a3 ~ ~ ~").s("sub_bass"));

blank("house");
tempo(120);
track("low", note("a1 ~ ~ ~").s("sub_bass"));

Both are the note A. The second is two octaves lower, and on good headphones or speakers you feel it more than you hear it. sub_bass is a pure, round synthesizer bass, which is why it nearly disappears on laptop speakers.

One note per bar

Our song will move through four chords, one per bar: A minor, F, C and G. You will build those chords on the next page. The bass plays the note each chord is named after, its root: A, F, C, G.

blank("house");
tempo(120);
key("A minor");
track("kick", s("bd*4"));
track("bass", note("<a1 f1 c2 g1>").s("sub_bass"));

The angle brackets < > mean “one per bar, in turn”: A in bar 1, F in bar 2, C in bar 3, G in bar 4, then A again. Each note lasts its whole bar. Listen to how the music seems to change mood every bar, even without chords: that is the bass doing its second job.

c2 is higher than a1 and g1, so the line moves down, up, down without big jumps: A, then F a little below it, C above, G below again. Keeping a bass line in a small range makes it smooth.

Rhythm

A bass that holds one note per bar is a drone. Give it a rhythm with .struct(), which takes the notes from one pattern and the timing from another:

blank("house");
tempo(120);
key("A minor");
track("kick", s("bd*4"));
track("bass", note("<a1 f1 c2 g1>").struct("x ~ ~ x ~ x ~ ~").s("sub_bass"));

"x ~ ~ x ~ x ~ ~" divides the bar into eight steps, two per beat, and plays on three of them. Count one and two and three and four and: the notes fall on one, on the and after two, and on the and after three. Each x plays whatever note the bar has. The first note lands with the kick on beat one, so you hear the chord change exactly when the bar starts; the other two fall between kicks, which is what makes the line groove.

Note length

Each note lasts until the next step unless you shorten it. .legato(0.5) makes every note half as long, so the bass bounces instead of sliding from note to note:

blank("house");
tempo(120);
key("A minor");
track("kick", s("bd*4"));
track("bass", note("<a1 f1 c2 g1>").struct("x ~ ~ x ~ x ~ ~").s("sub_bass").legato(0.5));

Bass sounds

Swap sub_bass for each and listen. On laptop speakers, organ_bass and saw_bass come through much more clearly, because they have higher overtones on top of the low note.

Try this

• The house offbeat bass: .struct("~ x ~ x ~ x ~ x"). The bass plays on every and, between the kicks, and the kick and bass take turns.
• Octave jumps: note("<[a1 a2]*4 [f1 f2]*4 [c2 c3]*4 [g1 g2]*4>").s("saw_bass").legato(0.5) jumps between the root and the same note an octave up, four times a bar: an eighties sound.
• Start the bass a sixteenth late with .late(0.0625) and hear the groove lean back.

The song so far

blank("house");
title("First Light");
tempo(120);
key("A minor");
track("kick",   s("bd*4"));
track("clap",   s("~ cp ~ cp"));
track("hats",   s("[~ hh]*4"));
track("shaker", s("sh*16").gain(0.4));
track("bass",   note("<a1 f1 c2 g1>").struct("x ~ ~ x ~ x ~ ~").s("sub_bass"));