"How many times have you wished you could make music? Well now you can! All you need is a tape recorder, some relatively simple skills, some curiousity, and a little imagination. This book has been used in classrooms throughout the country by students, many of them without previous experience in music, who are now composing electronic music projects. In this book you'll be taken into the exciting world of electronic music and you'll find the basic tape recorder as well as synthesizer techniques, explained in many step by step instructions, and a variety of experiments to help you make electronic music. You'll also find a whole set of composing projects where your own creativity can run free and you' will wonder why you didn't start sooner."

The Synthesizer

is a combination of oscillators, filters, ring modulators, etcetera, which are all devices invented that were developed individually over time.

When enough components had been invented for controlling all the elements involved in the creation of sound, they were compiled into a single unit and called a synthesizer.

Even though now the machine has a standardized name, the individual components are still called oscillators, generators, filters, and so forth. They make up the three basic foundational modules of synthesis building blocks:

Sources: produce the raw materials of sound in the form of basic waveforms

Modifiers: modify or alter these waveforms in a variety of ways

Controllers: control or regulate the actions of both sources and modifiers

Voltage Control

In the same way pressure drives a flow of water or steam through pipes an electromotive fore called voltage drives electric current through the circuitry of any device that uses electricity as its power source.

Working with a synthesizer, the composer can regulate a components by hand or they can take advantage of automating voltage control for accomplishing the same task with a higher degree of precision and speed impossible with manual control. For example, you can open or close switches by hand, or turn a volume knob, yet voltages can perform operations at the rate of several hundred or even several thousand times pers second. Because this driving force can be applied in a vast number of ways to affect all of the elements of sound frequency, timbre, amplitude, and duration; the advantes to the composer are enormous.

Some of this choice (manual control versus voltage control) is determined by the peticular components being used, since not all components produce voltage and not all components can be voltage controlled. You must use a control voltage source for regulating a voltage controlled unit.

We will discuss this important interaction in greater detail. To start, however, not the labeling on the synth control panels for three of the most essential voltage controlled modules: VCO, for voltage controlled oscillator; VCF for voltage controlled filter, and VCA, for voltage controlled amplifier.

Sound Sources and Processes

Oscillators

The three main bodies of components used to synthesize sound are typically installed on the control panel for left to right(the same path taken by the audio signal as it moves across the sound production circuits. In order, these are the sound sources, the sound modifiers, and the controllers.

The synthesizers principal sound sources(some of which may also function as voltage controlled sources) are the oscillators. These produce for typical basic waveforms(sine, triangle, sawtooth, and square) with individual timbres, controlling frequencies, and fixed ampolitudes.

The frequency of the selected waveform(which can be regulated by manual or voltage control) can be anywhere in or out of the audible range: from sub audio frequencies below 20 hz to ultrasonic frequencies above 16,000 hz.

Noise Generators

The noise generator produces a mixture, called white noise, resembles the hissingwhen found tuning between radio station frequency bands. (Sound waves producing noise emitting from the very Sun nin our solar system) Since the ear is more sensetive to high frequencies, white noise seems high pitched. Some of the high frequencies can be finltered out to obtain a more audibly balanced mixture called pink noise. Noise is used mainly for creating percussive type effects and to colour other sounds.

Frequency Modulation

Modulation in general is a form of control. In the case of sound sources, modulation is controlling the frequency, either manually or with control voltage from other sources.

For example, the frequency of one oscillator signal can be voltage controlled by the signal of a seconf oscillator. The one being controlled is called the audio signal, or carrier; the signal which does the controlling is called the modulator, or program signal.

In this interaction of two signals, it is the modulator's waveform that determines the frequency change of the carrier. In fact, you can actually hear the controlling waveform if its frequency is sub audio: Sub audio sine waves produce a frequency change in the carrier that smoothly rises and falls in effect a siren sound.

Sub audio triangular waves produce a frequency change that gradually rises, the immedeately begins a gradual fall. Sub audio rectangular or square waves produce a frequency change that abruptly alternates between two frequencies, with no perceptable sloping. Sub audio sawtooth waves produce a frequency change that gradually rises the abruptly falls.

If, however, you increase the frequency of the modulator into the audio range, you no longer hear its waveform yet now hear an entirely different result: the generation of frequencies in addition to the carrier and modulator frequencies. These additional frequencies, called sidebands, are non harmonic overtones which produce complex new timbres. Besides frequency modulation, there are two other modulation techniques.

Modifiers and Processes

Filters and Subtractive Synthesis

Sound sources can be used alone or in combination , as is or modified in a number of ways. one modification process, called subtractive synthesis, involes use of synthesizer audio filters. Filters are modifiers that change the timbre. they do this by subtacting any part of the frequency range of any sound above or below a variable cutoff point. Depending on the filter, the cutoff point can be manually controlled, or both manually and voltage controlled.