What is an Analog Modular Synthesizer?


Within an Analog Synth there is no digital storage of sounds, no memory, RAM, ROM or computer processing. Sounds are generated, processed and controlled by Analog circuitry.

This synthesizer creates sounds through 'subtractive synthesis'. Every sound it makes starts with with a basic waveform which is altered by removing certain harmonics by filtering. That waveform is then manipulated in frequency and amplitude to mimic other instruments or create new sounds. These sounds made by this instrument can be familiar, unusual, musical, noisy, unique, annoying, and/or fascinating.

Each 'module' of this synthesizer is a self contained, independant device. Individual modules generally perform one a specific function or a few related functions. Modules generally fall into three catagories, Sources, Processors or Control.

Many of the modules utilize "Voltage Control". I followed the standard of '1 volt per Octave' (1V/Oct) in this synthesizer. That means that for each additional increase of 1 volt applied to the voltage control input of an oscillator, the frequency of that oscillator will rise 1 octave.

Voltage control allows the output of one module to control parameters of other modules. Very Cool.

There are no audio or control connections built into the system. Physically 'patching' the modules together in various ways determines the sounds made. Patching is done with 'Patch Cords' terminated with 1/4 in phone plugs.

Some of the common modules found in analog modular synthesizers include;

VCO - (Voltage Controlled Oscillator)
The oscillator creates the audio frequency waveform that is manipulated with other modules. Voltage controlled means that you can pass a voltage into the module and control the pitch.

VCF - (Voltage Controlled Filter)
The VCF is a module which removes or attenuates certain frequencies in a sound to change its timbre. By using a control voltage the frequency of effect and resonance can be altered.

VCA - (Voltage Controlled Amplifier)
With a VCA you can adjust the amplitude of a waveform or control voltage. This can be done manually or by Voltage Control.

LFO - (Voltage Controlled Low Frequency Oscillator)
LFO's create slowly oscillating waveforms. They can be used to add vibrato or tremello to audible waveforms among many other uses. Voltage control allows you to speed up or slow down the oscillations.

EG - (Envelope Generator)
The Envelope Generator creates a one contoured control voltage when triggered. It may be triggered manually, or by another module, keyboard or sequencer. These control voltages are used to provide more complex control of volume, filtering or any other voltage controlled parameters than just ON/OFF.
I use AR (Attack/Release) EG's, or ADSR (Attack/Decay/Sustain/Release) in this synth.

A basic, conventional patch would use a 1V/Oct output from a Keyboard into a Voltage Controlled Oscillator (VCO) into a Voltage Controlled Filter (VCF), into a Voltage Controlled Amplifier (VCA).

Although that is a very generic example, the outputs of these modules are built to standard levels, so any output may be used as a signal or control source for another module. An oscillator output may be used as a signal, or a control for other modules.

This is the interesting part of synthesis! There is no right or wrong way to patch this synthesizer - some patches may not make any useful sound - but being creative in patching allows you to make sounds no one else has experienced.

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