Oscillator
The oscillator is the starting point for virtually all synthesis. Oscillators generate a fast, repetitive signal that we hear as a waveform. For example, it could be a smooth, undulating sine wave, a sharp sawtooth wave, or a square wave. Different oscillator modules offer different waveforms and controls to shape the sound they produce.
In modular synthesis, most oscillators must be combined with other modules to create a convincing sound. These additional modules will communicate with the oscillator via CV signals, allowing you to control the pitch and envelope of the notes produced.
More sophisticated oscillator modules give you access to more specialized and adventurous forms of synthesis, such as additive synthesis and FM. Depending on the type of sounds you want to produce, you can also explore other sound generators for your modular synthesizer: for example, a module that plays samples or a module that generates drum sounds.
Amplifier (VCA)
An amplifier module is used to control the volume of other modules – usually oscillators. In their basic state, most oscillator modules in modular synthesis simply emit a continuous tone. You need to tell the module when to play a “note”. You can do this by sending it volume signals with an amplifier module. This fundamental task makes amplifier modules one of the simplest and most essential components of a modular platform.
Envelope generator (EG)
An envelope generator can be used to change parameters over time – like the volume of your synthesizer sound – using editable shapes called envelopes.
Envelopes give contour to a sound. When you hear a synth bassline with a sharp attack that quickly fades, or a pad that comes in slowly and lingers for a while, you’re hearing an envelope at work.
An envelope generator is likely to perform at least two tasks in your modular platform.
First, an EG patched to an amplifier will allow you to shape the volume of each synthesizer “note” over time. Every time you want to play a note, you’ll need to trigger the envelope generator, which sends volume commands to the amplifier, which in turn changes the volume of the oscillator signal.
That’s right: just to play “notes” with a modular synthesizer, you’ll probably need at least three modules: an oscillator, an amplifier, and an envelope generator.
The other common task of an envelope generator is to control the filter cutoff. But the flexibility of modular synthesis means you can get creative with how you use envelopes by connecting them to other parameters. For example, try hooking up your EG to oscillator height to produce bright laser sounds.
The most common form of envelope is ADSR. But there are many types of Envelope Generator modules, offering awesome envelope shapes and in-depth customization.
Other modulators
An envelope generator is a type of modulator. This means that it is a module that does not generate or process audio itself, but rather sends commands to other modules to make them behave in a certain way. Modulation is an essential part of all synthesizers. By making synth sounds move, modulation helps them sound lively and unpredictable.
Your modular setup should have at least a few modulation modules. If you’ve used other types of synthesizer, you’ll be familiar with the other common type of modulator: the low-frequency oscillator (LFO), which produces a slow up-and-down signal that’s ideal for drifting and shimmering your sounds.
In most conventional synths, you can only assign your modulators to a few parameters. A modular synthesizer allows you to insert your modulator anywhere it receives a modulation signal. This allows you to create complex routings and surprising sounds. You can even modulate your modulators, using (for example) an LFO to change the depth or frequency of another LFO. This is when modular synths start to take on a life of their own.
Filter (VCF)
Filters shape the frequency content of a sound. They can do this by removing all high frequencies above a certain point in the frequency spectrum (in the case of a low pass filter) or by removing unwanted low frequencies (high pass filter).
Filters play a crucial role in any synthesis, shaping the raw sound that comes out of an oscillator to make it softer and more controlled. Analog (or analog-modeled) EQs can also add character to the sound, especially when you start to increase resonance (stiffness of the filter peak).
Most modular synthesizer setups will need at least one filter. Preferably low pass, although many manufacturers offer “multi-mode” filters which can adopt different filter shapes for added versatility.
Try controlling a filter with an envelope generator to make the frequency profile of your synthesizer sound change over time. But be careful: if you’re already using your envelope generator to control your amplifier, you may need to get a second EG to control your filter.
Triggering
One thing that sets a modular synthesizer apart is what it doesn’t have: a keyboard. You can add one if you want, by connecting a MIDI keyboard to your rig using a MIDI to CV interface (which translates your MIDI notes into messages your rig can understand).
But there are other ways to tell your computer what to do. A sequencer is a module that generates a series of predetermined signals to create looping patterns. Sequencers can be used to program melodies, rhythm patterns, etc. and are perfect for creating multi-layered music when you only have two hands. The most complex and exciting modular patches rely on clever use of sequencers.