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Using Sequencers (Part 2)


In the first article in this series, we mentioned briefly some of the problems involved in programming pieces of music containing triplets. Now we're going to look more closely at this and a musical technique which relies on it, that is, introducing a 'swing' feel. Although this is a term, and indeed a technique, which comes from jazz, many rock and pop musicians unconsciously write and perform numbers based on this feel. Not having had any jazz training, or perhaps even classical music theory, which would allow them to analyse what they are doing when they play like this, they continue in blissful ignorance until the day when they try to enter a 'swing' piece, or even a single 'swing' phrase into a sequencer.

Emerson, Lake and Palmer's version of 'Fanfare for the Common Man' is a good example of a piece of classical music which takes on a swing feel and Jacques Loussier is always doing it to Bach. The bass-line in the first example is actually the 'swing' quavers (crotchet triplet followed by quaver triplet) - we shall look at that in a minute and with the Loussier it is usually the ride cymbal which plays this phrasing.

So what exactly is 'swing'? Jazz musicians have many colourful phrases to describe it, but for our purposes it is perhaps best analysed in terms of standard musical notation. You will see the shorthand for it just above the first piece of music. Normally when smaller divisions than a crotchet are played, two quavers for example, they are all allotted an equal length of time. Previous to this century, any other playing style would have been considered poor timing or sloppy technique. But what jazz musicians began to do was 'lean' more heavily on the beat (the first quaver, say) extending its official duration at the expense of the off-beat, ie. the second quaver of two. The way we measure this can be expressed as a percentage, in the same way as we refer to the positive component of a pulse wave as part of the total wavelength, ie. how much of the total crotchet the first quaver takes. Fifty per cent is the 'no-swing' amount where the first and second quavers are equal (like a 50% pulse wave, eg. a square wave, where positive and negative components are of equal time duration). Normal 'swing' range, if you look at it like this, is between 50% and 70%, with the effect becoming more and more marked the higher the percentage. Lower than 50% would presumably be 'contra-swing' with the second quaver longer than the first. 75% would of course be a dotted quaver followed by a semi-quaver and technically, therefore, no longer a 'swing' feel.

The most common 'swing' amount is 66%, and this of course is two-thirds followed by one third. But because classical musical notation has a symbol for a one-third note, a triplet, we could write this in 'proper' notation. For each quaver note on the beat we would put a crotchet triplet and instead of the off-beat quaver, a quaver triplet. However, as each triplet note (however long or short) requires marking with a figure three above it, this would considerably increase the complexity of the musical score and the time it takes to write out. So we adopt the notation shown below (a pair of quavers equalling a crotchet triplet, followed by a quaver triplet) as a form of shorthand telling us to 'swing it'.

Here is a 'swing' phrase written out first in the shorthand version and then how it is actually played. Notice how the upper crotchets are not affected by the 'swinging' and it is really only the E which gives the phrase its 'swing' feel:

So how do we actually go about putting this piece into a sequencer? We know already that to program triplets we need to allow more clock pulses for each bar and to compensate by running our clock faster, but fortunately with 'swing' we don't have to allow for quavers mixed in with quaver triplets. So we can get away with 3 pulses per beat (12 pulses per bar). Now we must program every on-beat quaver for 2 pulses and every off-beat quaver for one. Note that crotchets now take 3 pulses, minims 6, and breves 12. So our three programming lines come out like this:

C h h C h h B h h B h h)
A h h A h h G h h G h h) repeat (ie. loop)
r r r r r E r r r r r E)

Have a listen to how this sounds (with a piano or other percussive-type sound) and then try programming the phrase as it is written (ignoring the swing abbreviation) ie. with 8 pulses to the bar, like this:

C h C h B h B h)
A h A h G h G h) repeat (ie. loop)
r r r E r r r E)

Hear how plodding and ordinary this sounds in comparison to the first phrase? This is the peculiar magic of 'swing' - it breathes new life and feeling into the simplest, most banal phrases.

Of course, it is also possible to program in different swing amounts into our sequencer. On several drum-machines currently available, it's possible to set a swing percentage between 50% and 70% as an auto-correct feature (on the Oberheim DX and SCI Drumtraks, for example). Unfortunately no one has developed the software to do this on a sequencer yet, so we have to do it the hard way. A 60% swing could be programmed by allowing 5 pulses per beat (20 per bar) and giving the first quaver 3 pulses and the second quaver 2. Our phrase would now be programmed thus:

C h h h h C h h h h B h h h h B h h h h)
A h h h h A h h h h G h h h h G h h h h) repeat (ie. loop)
r r r r r r r r E h r r r r r r r r E h)

However, the fifth-notes (used to program this 60% swing) use up memory space even faster than triplets and to get other swing values, you would need to use even more pulses per bar (40 for 55%, 60%, 65%, and 70%) and 100 for 52%, 56%, 64%, 68%, and 72%). Of course, by now we are into diminishing returns, for each minute extra subtlety we pay dearly in terms of memory space and number of bars.

Let's return to our phrase programmed with the more common 66% swing. Here's a bass-line to go with it, which containing nothing smaller than crotchets is independent of any swing amount:

If you're programming this on a separate sequencer and you can arrange a 3 to 1 clock divide (ie. the polyphonic sequencer is triggered three times as fast as the bass sequence) then you can save memory space and program it like this:

A h h h h h E G (repeat 6 times)
F h h h h h F G F h h h h h G h (repeat all ie. loop)

However, if it is on the same machine you will have to put three things in for every symbol above ie. A (h h) h (h h) h (h h) h (h h) h (h h) E (h h) G (h h) etc. Try more sustained sound, perhaps with PWM or a slow filter sweep on this languid bass-line.

Now let's add a melody line, which can be played over the top in real-time or programmed in step (pulse). Leave 4 bars before you begin playing:-

If you want to program this on the sequencer here are the step-by-step instructions (put in 48 rests first):

D E A r r r r r r r r r r r r r r r E r D r C r A r r r r r E r r r r r r r r r r r r r r r r r (repeat)

D E A r r r r r r r r r r r r r r r B r C r A r r r r r E r r r r r r r r r r r B r C r B r

A r r r r r E r r r r r r r r r r r E b r D r C r A r r r r r r r r r r r r r r r r r r r r r r (repeat all ie. loop)

Use a smooth brassy sound to play this melody. The observant amongst you will notice that the grace note at the beginning uses up one triplet space and the next note which it steals from also has one triplet space. The A, which would have fallen on the third triplet anyway, then takes its normal place.

You may also have noticed that whilst the chords and bass-note change the repeated one-bar sequence doesn't. This is a very common technique especially when using sequencers with traditional instruments. Good examples of this are 'On The Air' and 'San Jacinto' by Peter Gabriel. We will be looking at more complicated examples of this compositional technique in the next instalment. Until then, happy sequencing.

'Film Theme' Copyright 1983 Paul Wiffen


Read the next part in this series:
Using Sequencers (Part 3)

Previous Article in this issue

Seiwa SR100 Rockman Guitar

Next article in this issue

S-Trigger Converter Project

Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.


Electronics & Music Maker - Mar 1984




Using Sequencers

Part 1 | Part 2 (Viewing) | Part 3

Feature by Paul Wiffen

Previous article in this issue:

> Seiwa SR100 Rockman Guitar

Next article in this issue:

> S-Trigger Converter Project

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