The inspiration for modular synths date from the era around the 1970's, when engineers were trying to incorporate the discoveries of the electronic semiconductor revolution into the music field. In order to explore the physics of music, they designed modules that attempted to electronically reproduce the functions of non electronic instruments (acoustic).
They soon discovered that if they made the important functions of the modules voltage controllable, they were MUCH more interesting and more musical. In addition, they added gates and triggers to turn the modules on and off and to start module events. Connections between modules were made with patch cords. In order to provide the most flexibility, most designers opted to use control voltage and audio levels that were the same. That enabled the use of audio for CVs (control voltages) and CVs for audio.
The original modulars were handmade in very limited numbers and were very expensive. They inspired the creation of best selling keyboard instruments such as the MiniMoog and Sequential Circuits Prophet. Although briefly popular, they faded before the onslaught of cheap off shore digital keyboards.
Modulars were rediscovered in the mid 1990s and became prized for their analog sound and radical appearance. The early units soon started to be discovered in garages and university storerooms and began to fetch astounding prices. A few dedicated designers started building modulars again, using modern components and up to date quality standards.
Today there is a myriad of available modules. The most common are the VCO (Voltage Controlled Oscillator) for sound generation, the VCF (Voltage Controlled Filter) for altering sound harmonic content, the VCA (Voltage Controlled Amplifier) for altering volume and the ADSR (Attack, Decay, Sustain, Release) for providing an envelope or changing control voltage to control the modules.
Looking through the information on manufacturer web sites will provide insight on the other modules available and give you some idea of the versatility of a modular system.
VCOs from two of the most popular module manufacturers:
Blacet Research and Synthesis Technology (MOTM)
|Note the difference in module size, jack size and knob size. This represents
an ergonomic design tradeoff (size, weight and portability vs ease of access
for controls and patch cords) that often influences the purchaser.