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Back to Basics (Part 1)

We start a new series on synthesis for the complete beginner. Steve Howell is the man at the helm.


Or everything you always wanted to know about synthesisers but were afraid to ask. If you're new to the world of electronic music, this new series is for you.

The Roland SH101 - one of the most popular beginner's synths ever produced.


So there you are, listening to the radio, watching Top of the Pops (more fool you!), and all the while being exposed to a mysterious musical instrument that seems to be the key to fame, fortune, nubile women, large amounts of smoking substances of dubious legality, and the opportunity to do no more real work for the rest of your life. Further enquiries yield the following information: the instrument in question is the synthesiser.

Once you've learned how to pronounce it, you make haste to your local music store, cash in hand (the bank manager is friendly), and on entering are confronted with a bewildering array of hi-tech machinery that seems about as easy to get to know as a Yugoslav railway timetable. Worse, the equipment possesses a unique terminology so complex that it could easily pass for an ancient ritualistic version of Serbo Croat.

Undeterred by all this, you hand over your money and walk out, the proud owner of one of these said instruments. You take it home, remove the machine's attendant polystyrene packaging (good for lining cat litters, this), and discover to your horror that even connecting the synth to the mains poses problems.

In search of help, you make a quick sortie on the local newsagent, whereupon you discover a smart, colourful and neatly-packaged periodical by the name of Guitarist. There are no synthesisers in it, so you put it back, picking up in its place the January issue of Electronics & Music Maker which, to your complete and un-precedented astonishment, contains the first in a series on how to get your synthesiser working. In the beginning, from the ground up, and for the complete novice.

The Prophet 5 - analogue synthesis applied to a polyphonic instrument. Programmable memories made it an overnight success.


The Theory



It's pretty obvious that if you want to get the most out of any musical instrument, you need to know as much about it as possible. This is especially true of synthesisers, as not only do you have to get your musical ideas into shape (can't help much with them, I'm afraid), you also need to be at least reasonably familiar with your model's technical operation.

Don't panic. This isn't nearly as difficult as it might appear at first, and will not require a degree in quantum astrophysics: the rules, such as they are, are actually quite straightforward.

Now for the boring bit.

Contrary to semi-popular belief, synthesisers have been with us for rather a long time - it could even be argued that they date back to the simple keyboard instruments of the Middle Ages - experimentation with electronic sound beginning at the turn of the century with such instruments as the Telharmonium and the Ondes Martenot. These were impressive machines that incorporated valves the size of large lightbulbs and allowed some quite intriguing creative projects to be realised, but further progress was lamentably slow: even in the fifties, composers such as Varese and Stockhausen were messing about (academics call it 'experimenting') with sound generators and tone controls of an extremely basic nature.

It wasn't until the mid-sixties that a gentleman by the name of Robert Moog (pronounced as in Vogue, by the way) produced the first instrument we'd recognise today as a synthesiser. He succeeded in assembling a complete synthesiser system comprising the basic building blocks of sound, and these could be linked together (the process is often referred to as 'patching') in an almost infinite variety of permutations.

The major difference between Moog's work and those of competing designers was his rationalisation of the way in which these synth modules could be connected and manipulated. His theories were based around a system known as 'voltage control', and this principle has, as it turns out, formed the basis of almost all analogue synthesisers ever since.

Figure 1. The effect of applying a slowly rising and falling voltage to the input of a VCO.


The principle is based on the theory that applying a voltage to any voltage-controlled unit will have some sort of effect on that unit. In other words, if you apply a rising and falling voltage to the voltage control input of an oscillator, the pitch of that oscillator will rise and fall accordingly (and for those for whom even a thousand words cannot convey an image accurately, this action is shown in Figure 1).

Figure 2. Typical analogue synthesiser layout.


Figure 2, meanwhile, shows the basic layout of a typical synthesiser in the form of a block diagram. Boxes with a heavy outline show the path of the audio signal, while those with a lighter border indicate purely controlling modules. Turning our attention first of all to the audio signal, it's useful to remember that any sound is made up of three different components - pitch, tone and amplitude. An analogue synth allows you control of these parameters through its VCO, VCF and VCA sections, and the signal passes through these oscillators, filters and amplifiers in turn.

Voltage-controlled devices may have various controllers routed to them and in amongst these you should find a low frequency oscillator (LFO), an envelope generator or two, and of course the keyboard itself. Controllers generate voltages which are then applied to voltage-controlled modules, and, logically enough, the more VC modules that can be affected by each controller, the greater the sonic possibilities your synth will be capable of producing.

Obsolete but still available in some shops, the Korg MS20 was essentially a modular synthesiser in miniature. Its patching section forms an excellent guide to the principles of analogue synthesis.


The Practice



If you've just bought your first synth, chances are it'll be of the analogue, monophonic variety - examples of this are the Roland SH series, Korg's MS10 and 20, and all the monosynths from the Yamaha and Moog stables, among others. All these instruments make use of the analogue synthesis principle I've just been discussing, as do a surprisingly large number of today's polyphonic synthesisers.

The major difference between mono and polysynths (as most of you are probably already aware) is that whereas the former only allow you to play one note at a time on the keyboard, polyphonic instruments allow you to play four or more. Obviously, in order to facilitate this, a polysynth has to have at least as many oscillators as it provides voices: some provide two oscillators for each voice in the interests of fattening the instrument's sonic output.

As it happens, analogue polysynths (even those that use digitally controlled sound generators and modifiers) don't differ all that greatly in method of operation from their monophonic counterparts: examples of such instruments are the Korg Polysix, Roland Jupiter series, and SCI's highly-successful Prophet models.

It's not beyond the realms of possibility that your first synth has rather more in the way of facilities than the 'typical' instrument shown in Figure 2. The standard VCA and VCF sound modifiers are often supplemented by onboard signal processors such as chorus, phase shifting and flanging units, while almost all synths have some form of pitch-bender to augment the pitch control already provided by the keyboard.

But whatever your newly-acquired synth has come equipped with, none of it is so mind-bogglingly complicated to prevent you from getting the most out of it. Or at least, it shouldn't be if you carry on reading Back to Basics...


Series

Read the next part in this series:
Back to Basics (Part 2)



Previous Article in this issue

Short Circuit

Next article in this issue

Patchwork


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

 

Electronics & Music Maker - Jan 1985

Scanned by: Stewart Lawler

Topic:

Synthesis & Sound Design


Series:

Back To Basics

Part 1 (Viewing) | Part 2 | Part 3 | Part 4 | Part 5 | Part 6 | Part 7


Feature by Steve Howell

Previous article in this issue:

> Short Circuit

Next article in this issue:

> Patchwork


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