Classes of Sound Generators

Electronic Music Basics

Most of us know the ABC of the electronic music. For example sine, saw, square and noise wave forms are used in traditional sound synthesis and accompanied by a variety of filters and envelopes. For example: ADSR – Attack, Delay, Sustain and Release, also CV – Control Voltage, High Pass and Low Pass, as well as delay, reverb, unison, chorus and phaser. Variations of synthesized wave forms can produce a wide range of sounds, both digital and natural sounding, especially when dealing with polyphonic synthesis.

Polyphonic synthesis is nothing revolutionary. It simply means that the synthesizer is capable of generating multiple sounds at once. For example press two or more keys on a monophonic synthesizer and you will only get once sound at a time. Although more limiting monophonic synthesis has its advantages and unique tight control over sound, where as polyphonic synth can be a bit of a handful to manage when working with delayed sound. Let’s say they both have their own advantages and disadvantages.

New experimental and hybrid synthesis methods soon followed. Three examples are modular, subtractive and granular synthesis. Each one challenges the traditional means of generating electronic sound by re-inventing, tweaking, upgrading or combining the standard set of sound waves.

Analogue and Digital

Electronic music can be divided into two broad technical categories: analogue and digital. Yes, we’ve heard of these terms many times but what is the difference between the two? One is old and one is new, you may say – and not be wrong about it. However there is a lot more to it than just the age of course. First of all, analogue electronic music is a lot closer to natural sound in the way the sound is being generated.

Analogue Instruments

Let’s use analogy in describing analogue electronic music. We’re all familiar how a flute works. The air is being pushed through a hollow pipe with several exit holes. As the air particles leave the instrument they collide with the walls and other air particles generating oscillations which we perceive as sound. Combination of the holes determines the pitch by changing the way the air escapes the instrument. The volume is determined by the intensity of air pressure applied to the instrument.

Electronic instrument uses an electrical current instead of wind. Electricity passes through a variety of electronic components such as switches, triggers, capacitors, oscillators, tubes and/or integrated circuits which all adjust the flow of the electric current and shape the sound accordingly. Naturally, such output is not very strong or audible until connected to an amplifier and a set of speakers which generate that final physical vibration of the speaker membranes which stirs up the air molecules and allows us to hear the output. It’s important to mention that analogue electronic music instruments have limited flexibility. For example to make your analogue synth sound different you would most likely have to patch it in a different way or rewire a few things. Analogue synthesisers have a set number of present sounds which can be adjusted in a number of ways but once tweaked it may be hard to find the original state. You will often find that the sound of an analogue synthesizer changes over time both short and long term. One being cause by your equipment literally warming up, the other by aging components. It’s not a complete surprise to find an old synth slightly out of tune. In fact every time you press a key on the keyboard you get a slightly different sound, with mostly subliminal effect. Some call it ‘air’ or ‘warmth’. So in summary, analogue electronic instruments are actual physical instruments that use electricity to trigger sound. Not everyone has them at home as they are generally heavy, expensive and high maintenance.

Digital Instruments

Digital electronic instruments are a new generation. Although they share certain components with analogue instruments, these machines are far from natural instruments and a lot closer to computers. The reason for this is that they code the sound information rather than producing it on the fly. Technically one sound triggered million times can in fact sound exactly the same. They are perfect every time and have a vast variety of sounds in their memory. Just like computers, digital instruments store sound information rather than sound in their memory. The information is written in binary language using data bits that mark ON and OFF state or 1 and 0. Combinations of data strings are then interpreted by a central processing unit which instructs on how to generate the sound.

Digital instruments are generally compact, portable and compatible with a variety of inputs and outputs (midi, optical, audio, data) as well as storage and recording options. Digital electronic music instruments owe their popularity to low prices and portability which is great when performing live, collaborating or moving your studio. Audiophiles tend to criticise pure digital sound as soulless and artificial. Today there is a variety of plug-ins and modules that mildly spoil or randomise otherwise perfect sound in order to make it more natural sounding. In most digital instruments today you will also find at least one emulated analogue synthesiser.

Virtual Instruments

Finally a third and fastest growing family of instruments are virtual instruments. These are neither analogue nor digital devices but a software sub-set of digital family of instruments that can (arguably) emulate both with quite a high level of accuracy. At this level musicians need no more than their computers to write and perform music. Virtual instruments still need computers for processing power and interfacing with the sound generators and speakers. Considering our physical limitations and bodies we naturally still need clunky interfaces to be able to adjust and play sounds. Compact MIDI interfaces and keyboards seem to be doing a pretty good job at this and can be used with any compatible computer or software. Virtual instruments are neat, cheap, accessible and widely accepted as an alternative to expensive equipment.

Author: Dejan Petrovic

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