Journal 01

What swing is in music

Swing makes a beat lean. It delays every second sixteenth note, so the notes fall in pairs: one long, one short. How far it delays them is the whole setting, and it can be measured.

Fig. 1

One beat at 90 BPM, five settings, to scale. Steps 1 and 3 stay on the grid. Steps 2 and 4, in orange, arrive late by the time shown; the ring is where each would have been.

The idea

Count a bar in sixteenth notes, 1 to 16. In straight time every step is the same length. Swing leaves the odd steps where they are and moves each even step later. A pair of steps still takes the same time as before. The first step of the pair is longer and the second is shorter.

Nothing is added and nothing is removed. The same notes sound, and only the even ones move. That small lateness is what turns a stiff bar into one that leans.

How it is measured

Roger Linn put swing in his drum machines and in the MPC, and gave it a number. In his words: "I merely delay the second 16th note within each 8th note." He measures the delay as the first note's share of the pair. "50% is no swing, meaning that both 16th notes within each 8th note are given equal timing." "66% means perfect triplet swing, meaning that the first 16th note of each pair gets 2/3 of the time, and the second 16th note gets 1/3."

Beep Boop's SWING knob runs from 0 to 100 across the span from 50 to 75 percent. Each four points of SWING is one of Linn's percent.

Swing settings: Linn's percentage, Beep Boop's SWING, how late the even steps are at 90 BPM, and how it feels.
Linn	SWING	Late at 90 BPM	Feel
50%	0	0 ms	Straight.
54%	16	13 ms	Looser, and not yet heard as swing.
62%	48	40 ms	A lean. Linn's own example at 90 BPM.
66.7%	67	56 ms	A triplet: the pair is split two to one.
75%	100	83 ms	The knob's limit: three to one.

Linn on the small settings: "a swing setting of 54% will loosen up the feel without it sounding like swing." And on the middle of the range: "a 90 BPM swing groove will feel looser at 62% than at a perfect swing setting of 66%."

Why the tempo matters

The delay is a share of a step, and a step gets shorter as the tempo rises. At 90 BPM a sixteenth note lasts 167 milliseconds, so SWING 48 is 40 milliseconds late. At 70 BPM the same setting is 51 milliseconds late. At 140 BPM it is 26.

So one setting does not feel the same at every tempo. Players know this without the numbers: in jazz, swing is played wider at slow tempos and narrower at fast ones. On a drum machine the knob is turned by ear for the beat in hand.

Hear it

Three bars follow. The steps are the same in each: a kick on 1 and 11, a snare on 5 and 13, and a hat on every sixteenth. Only SWING changes. Press PLAY on each and listen to the hats.

Fig. 2

A bar at 90 BPM with no swing: the steps each voice plays, of sixteen.
Kick	1, 11
Snare	5, 13
Hat	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
Tempo	90 BPM
Swing	0 Straight. Every hat is the same distance from the next.

SWING 0. The bar as a machine counts it.

Fig. 3

The same bar at 90 BPM with SWING 48.
Kick	1, 11
Snare	5, 13
Hat	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
Tempo	90 BPM
Swing	48 Linn's 62 percent. Every even hat is 40 milliseconds late.

SWING 48. The same steps, leaning.

Fig. 4

The same bar at 90 BPM with SWING 67.
Kick	1, 11
Snare	5, 13
Hat	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
Tempo	90 BPM
Swing	67 A triplet. Every even hat is 56 milliseconds late.

SWING 67. The pairs are split two to one, as a shuffle is.

On Beep Boop

SWING is the knob at the right of the bottom row. It runs from 0 to 100, and the window shows the number as it turns. One setting swings the whole beat: every voice leans together.

The delay is counted in samples of sound, not timed by a clock, so it is the same in every bar. At 90 BPM and 48,000 samples a second, a step is 8,000 samples long. SWING 48 places each even step 1,920 samples late, every time.

For a beat that is built on swing, see the boom bap pattern, which sits at SWING 48.

Sources

Roger Linn's words: Greg Scarth, Roger Linn on swing, groove and the magic of the MPC's timing, Attack Magazine.
Swing in jazz, wider at slow tempos and narrower at fast ones: Swing (jazz performance style), Wikipedia.
The knob's rule and the sample counts: Beep Boop's engine, where SWING 100 delays each even step by half a step and every step is placed by counting rendered samples.