Early type of synthesizer consisting of seperate modules which must be connected by wires to create a so called patch. These synthesizers are very flexible. Instead of audio, every output generates a voltage (or a current). All inputs expect a voltage, so that almost any combination of connections between the modules is allowed and valid.
There exist many different modules and even the modules with the same function have different inputs and output on various models. But there are some standards which manufactures followed for their range of synthesizers. Connecting synthesizers from different manufactures often required converters however.
Some standard modules found on almost any synth are:
- VCO - Voltage Controlled Oscillator
- VCF - Voltage Controlled Filter
- VCA - Voltage Controlled Amplifier
- Envelope generator
- LFO - Low Frequency Oscillator
- Sample and Hold