SYNTHESIS MODULES

BY: ANDRÉS FERNANDO REGALADO BUCHELI

INTRODUCTION

Hello my friends, my name is Andrés F. Regalado Bucheli and this lesson is about the usage of the 5 mostimportant synthesis modules: Oscilator, Filter, Amplifier, Envelope and LFO. This modules are veryimportant, cause most of synthesis breaks down to these five modules and just various ways ofconnecting them.

Synthesis is better known as modular synthesis, because there’s theses simple building blocks thatconnect together. English is not my mother language but i will try to do the best i can with thispresentation. I hope you enjoy the lesson and good luck to everyone in this last week.

Regards

Andrés F.

SYNTHESIZERS

The analogical synthesizer is an

electronic musical instrument that

generates sounds with some

systems that we will see in this

presentation. This systems are

purely analogic in the electronic

sense. This useful and wonderful

device was invented before the

advent of digital technology we

know now.

BRIEF HISTORY OF SYNTHESIZERS I

1964 Moog invents the modular synthesizer.

As electronic technology advances, mainly the

transistor, it becomes posible to construct more

sophisticated sound generators. Thus Robert Moog,

in collaboration with a musician named Herbert

Deutsch, develops the first VCO and VCA

controlled by voltaje. A year later Moog develops

the VCF controlled filters, low pass and high pass,

the ADSR envelope generators and the memory

keyboards.

In October of that year, Moog presented at a

convention of Audio Engineering Society, his paper

entitled “Modules for electronic music controlled by

voltaje”

BRIEF HISTORY OF SYNTHESIZERS II

ELEMENTARY SYNTHESIZER’S BLOCK DIAGRAM

Three years later, Moog Music Inc.produced a complete line of veryversatile modules and easy to use toproduce sounds. In 1968 Walter Carlosintroduces the concept of laboratoryelectronic music and surprised the staffwith his version of Bach’s Brandenburgconcert and gets a big hit with hisalbum “Switched on Bach”, aprodigious display of electronicvirtuasity playing J.S. Bach music.

THE CONTROLLER KEYBOARD

The keyboard is the most popular controller for all type of synthesizers. This is a source that supplies proportionalvoltages to the key is pressed. In polyphonic synthsizers, most modern it is posible to get several controlvoltajes, one for each key pressed. They keyboard can aslo provide other control voltajes, such as the speed ofkeystroke or pressure on it, which increases the expresive posibilities of the synthesizer.

For operation of the set of modules, the keyboard provides various control signals.

- A trigger pulse, each time a key is pressed, which is used to start the envelope generators.

- A voltaje step of equal duration to the time the key is pressed, which generates maintenance signals andADSR generator relaxation.

- A discrete voltage level corresponding to the key pressed, thereby 1V corresponds to a difference of anoctave.

- A control signal, which lets you generate a slide between two notes.

- An analog memory that maintains the tension of the last key pressed.

THE VOLTAGE CONTROLLOED OSCILLATOR

VCO

This is the basic sound source of the synthesizer. The frequency of the generated signal is

obtained as the algebraic sum of the control voltages applied to its inputs. In the Synthesizers

VCO’s with normalized exponential response of 1V/octave are usded. It has several

waveforms, sine, sawtooth, triangle, square, and each gives a quirky and different sound type

given the different harmonic content they have.

THE AUDIO MIXER

Is a device that allows the combination of a number of input signals in the desired proportions

so as to obtain another signal which is the combination of those.

THE ENVELOPE GENERATOR ADSR

ADSR stands for attack, decay, sustain, release, and it refers to four areas of the amplitude

characteristics of a control signal. ADR areas refer to times, while S refers to a level. These

generators will control both the amplitude envelope of the sound signal and the response of

the filter.

THE VOLTAGE CONTROLLED FILTER VCF

The filter is an element that allows the passage of certain frequencies of the input signal, and

is the electrical equivalent of the traditional resonators of the acoustic instruments like violin

case, which gives the characteristic sound of the instrument. This filter can be configured in

several modes, low pass, high pass, band pass and band reject, according to the effect we

want to emphasize or weaken of the basic wave generated by the VCO.

The characteristic parameters of a filter are cutoff frequency, from which the response is half,

and the slope of the filter which determines the attenuation of successive harmonics of the

input signal.

THE LOW FREQUENCY OSCILLATOR LFO

Generally consists of several independent voltage-controlled oscillators, with various

waveforms each, and which are located in the low frequency range, up to about 20Hz. Its

output can be used both to control the amplitude, tremolo, such as frequency, vibrato, in the

VCOs, obtaining varied sonorities.

THE NOISE GENERATOR

They typically provide white and pink noise, as well as a random but adjustable in certain

parameters control voltage output. These three signals are used to produce unconventional

sounds similar to the natural, from the sea to thunder and the hiss of air.

REFLECTION

Synthesizers are very interesting devices from the point of view of electronic engineering and fromthe point of view of music and there is a lot of analog and digital signal processing a person candesign and experiment with. I think possibilities are infinite and only the human creativity puts thelimit. I admire so much people like Les Paul, Leo Fender, Robert Moog, Epaminondas Stathopoulo,Leon Theremin and all that wonderful people that contributed to the develep of music. I just wantto have the opportunity to pay a loving tribute to all this with this last presentation.

I hope you enjoyed this lesson my friends and my best desires for you in your future life.

Peace and Love my friends.

Andrés