Modular synthesizer
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The modular synthesizer is a type of synthesizer consisting of separate specialized modules connected by wires (patch cords) to create a so-called patch. Every output generates a signal – an electric voltage of variable strength. Combining the signals generated by multiple modules into a common audio output allows a potentially infinite number of configurations, leading to a potentially infinite number of sounds.
There exist many different types and sub-types of modules – even modules with the same basic function will have different inputs, outputs and controls on various models. There are some standards which manufacturers followed for their range of synthesizers; however, connecting synthesizers from different manufacturers often requires converters.
Some standard modules found on almost any modular synth are:
- VCO – Voltage Controlled Oscillator, which will output a pitched sound (frequency) in a simple waveform (most usually a square wave or a sawtooth wave, but also includes pulse, triangle and sine waves).
- Noise source - A generator that supplies "hiss" sound similar to static, which can be used for explosions, cymbals, or randomly generated control signals. Common types of noise offered by modular synthesizers include white, pink, and low frequency noise.
- VCF - Voltage Controlled Filter, which attenuates frequencies below (high-pass), above (low-pass) or both below and above (band-pass) a certain frequency. VCFs can also be configured to provide band-exclusion, whereby the high and low frequencies remain while the middle frequencies are removed.
- VCA - Voltage Controlled Amplifier, which varies the amplitude of a signal in response to a supplied control voltage.
- EG - triggering an Envelope Generator produces a single, repeatable shaped voltage pulse. Often configured as ADSR (Attack, Decay, Sustain, Release) it provides the means to shape a recognizable sound from a raw waveform. This technique can be used to synthesize the natural decay of a piano, or the sharp attack of a trumpet. It can be triggered by a keyboard or by another module in the system. Usually it drives the output of a VCA or VCF, but the patchable structure of the synthesizer makes it possible to use the envelope generator to modulate other parameters such as the pitch or pulse width of the VCO. Simpler EGs (AD or AR) or more complex (DADSR—Delay, Attack, Decay, Sustain, Release) are sometimes available.
- LFO - A Low Frequency Oscillator is similar to a VCO but it usually operates below 20 Hz. It is generally used as a control voltage for another module. For example, modulating a VCO will create vibrato while modulating a VCA will create tremolo.
- RM - Ring modulator - Two audio inputs are utilized to create sum and difference frequencies while suppressing the original signals. This gives the sound a "robotic" quality.
- Mixer - a module that combines multiple signals into one.
- S&H - Sample and hold, which takes a "sample" of the input voltage when a trigger pulse is received and "holds" it until a subsequent trigger pulse is applied. The source is often taken from a noise generator.
- Sequencer, which produces a sequence of notes, usually a music loop.
- Slew limiter - smooths off the peaks of voltages. This can be used to create glide or portamento between notes. Can also work as a primitive low-pass filter.
- Custom Control Inputs - Because modular synthesizers have voltage-driven inputs, it is possible to connect almost any kind of control. Pitch can be varied by room temperature if you wish, or amplification varied by light level falling on a sensor.
Modular synthesizers can be bulky and expensive, and there is a steep learning curve. Producing polyphonic music is painstaking and difficult, and, since patches cannot be saved, they are not easy to play live. In the late 1980s, modular synthesizers were largely replaced by highly integrated keyboard synthesizers, racks of MIDI-connected gear, and samplers. However, there continues to be a loyal following of musicians who prefer the physically patched approach, the flexibility and the sound of traditional modulars. LatelyTemplate:When? there has been a resurgence in the popularity of analog synthesizers; in fact, there are more manufacturers nowTemplate:When? than there were when they were at the height of their 1970's peak popularity.
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