Daniel Dehaan

Modular Synthesis Basics

one-sheetsynthesis-modularsynthesis-softwaresynthesis-concepts

Modular Synthesis: Basics

Common Modular Formats:

Rack Units:

A ‘U’ which is 1.75 inches (44.45 millimeters) high.

3U: Eurorack

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Module Height:

  • 128.5 mm / 5.06”

Module Width:

  • Measured in HP (Horizontal Pitch). 1HP = 5.08 mm / 0.2”

Typical Voltage Levels:

  • ±5 V for audio (and some control) sources
  • 0-10 V for control sources

Power:

  • ±12 V and + 5 V

Connector Types:

  • 3.5 mm TS cables/jacks

Origin:

  • Dieter Doepfer

4U: Serge

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Module Height:

  • 177.8 mm / 7”

Module Widths:

  • 1” / 25.4 mm increments

Typical Voltage Levels:

  • ±2.5 V for audio
  • 0-5 V for control sources

Power:

  • ±12 V

Connector Types:

  • 4 mm banna jacks/cables

Origin:

  • Serge Tcherepnin

4U: Buchla

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Module Height:

  • 177.8 mm

Module Widths:

  • Measured in units (U)
  • 1 unit = 107.95 mm / 4.25”

Typical Voltage Levels:

  • ±1.75 V for audio
  • 0-10 V for control sources

Power:

  • ±15 V, ±12 V, ±5 V

Connector Types:

  • 4 mm banana jacks for CV
  • Tini-Jax for audio

Origin:

  • Don Buchla

MU/5U: Moog and Synthesizers.com

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Module Height:

  • 222.25 mm / 8.75”

Module Widths:

  • 1,2,4, or 8 units wide
  • 1 unit = 55.98 mm / 2.13”

Typical Voltage Levels:

  • ±5 V

Power:

  • ±15 V, +5 V

Connector Types:

  • 1/4” TS jacks (audio and control sources)

Origin:

  • Robert Moog

Basic Concepts of Modular Synthesis

Everything is a voltage

Everything in a modular synthesizer is either a fluctuating or steady voltage. This means anything can be anything and any point at any time.

Audio Signals

Typically voltages that are changing faster than 20 times per second. And usually something that is meant to be heard, but doesn’t have to be…

Control Voltages

A stream of voltages that changes at a slower rate (less than 20 times per second) if it is changing at all.

1V/Oct

Most frequency, or pitch-related parameters within a modular synthesizer follow the 1 volt per octave standard. That means if an oscillator, for example, that is tuned to a frequency of 100 Hz receives…

  • 0 voltes at its 1V/Oct input = 100 Hz
  • 1 volt at its 1V/Oct input = 200 Hz
  • -1 volt at its 1V/Oct input = 50 Hz
  • 0.5 volts at it 1v/Oct input = 150 Hz

Timing

The tempo, rhythm, or other time-related events are often controlled with types of control voltages known as a gate or a trigger signal.

Triggers:

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  • A trigger signal is a short pulse that jumps almost instantly from 0 volts, up to 5 volts, and back to 0 volts.
  • A trigger signal is great for controlling the tempo/rate of some process

Gates:

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  • A gate signal is similar to a trigger signal, but unlike a trigger signal, a gate signal can remain at 5 volts for any period of time
  • Gate signals are idea for controlling how long something last (e.g. how long a note is held for)