Modular synth glossary

The words you’ll meet in every patch, in plain English. Each one links to a module you can try it on.

ADSR also: attack, decay, sustain, release

Attack, Decay, Sustain, Release: the four stages of the most common envelope.

Attack is how long it takes to rise when the gate opens. Decay is how long it takes to fall to the sustain level. Sustain is the level held for as long as the gate stays high. Release is how long it takes to fall to zero after the gate closes.

Try it: ADSR

Attenuator also: attenuverter, attenuate

Turns a signal down (or, as an attenuverter, flips it upside down).

Modulation is often too strong straight out of the box. An attenuator scales it to taste; an attenuverter can also invert it, so an envelope closes a filter instead of opening it.

Try it: Scale / Offset

Audio rate also: audio-rate

Fast enough to hear as a tone: roughly 20 Hz and up.

Modulation at audio rate does not sound like movement any more; it changes the timbre itself. That is the step from vibrato to FM, and from tremolo to ring modulation.

Clock also: tempo, BPM

A steady stream of triggers that keeps a patch in time.

Sequencers step forward, drums fire and envelopes start on clock pulses. Divide or multiply a clock to get different note lengths from one tempo.

Try it: Clock Clock Divider

Cutoff also: cutoff frequency

The frequency where a filter starts cutting.

Below the cutoff a low-pass filter lets sound through; above it, the sound is reduced more and more. Modulating the cutoff is one of the most expressive moves in synthesis.

Try it: Filter

CV also: control voltage, control signal, control signals

A signal used to control a parameter rather than to be heard.

In hardware modular, everything is voltage: audio, pitch, envelopes and LFOs travel down the same cables. A CV is any of those used to move a setting, like a filter’s cutoff or a VCA’s level. In Kables, as in a real system, any output can be patched into any input, so a sound can be a CV and a CV can be a sound.

Envelope also: envelope generator, EG, envelopes

A one-shot shape that rises and falls each time a note is played.

An envelope turns a gate (key down, key up) into a smooth contour. Patch it into a VCA to shape a note’s volume, or into a filter cutoff to shape its brightness over time. Plucks, pads and swells are mostly different envelope settings.

Try it: ADSR Env Follower

Euclidean rhythm also: euclidean, euclid

A rhythm that spreads a number of hits as evenly as possible over a number of steps.

Three hits over eight steps gives the tresillo, five over eight the cinquillo. Many traditional rhythms fall out of this one rule, which makes Euclidean sequencers a fast way to interesting grooves.

Try it: Euclid

Eurorack

The most common hardware modular format, with thousands of modules from hundreds of makers.

Eurorack modules share one size, power supply and voltage standard, so a VCO from one maker can be patched into a filter from another. The ideas you learn in Kables (VCO, VCF, VCA, envelopes, LFOs, CV and gate) transfer directly to a Eurorack case.

Filter also: VCF, low-pass, lowpass, high-pass, highpass, band-pass, bandpass, filters

Removes part of the frequency range, making a sound darker, thinner or more focused.

A low-pass filter lets the lows through and cuts the highs, so closing it makes a sound darker. High-pass does the opposite, and band-pass keeps only a band around the cutoff. Sweeping a filter with an envelope or LFO is the classic synth “wow”.

Try it: Filter Vowel Low-Pass Gate EQ

FM also: frequency modulation

Changing an oscillator’s frequency with another signal, often at audio rate, for bells and metallic tones.

Slow FM is vibrato. When the modulating oscillator runs at audio rate, the result is a new, complex tone with sidebands: bells, electric pianos and clangs. The FM amount sets how bright and inharmonic it gets.

Try it: VCO

Gate also: gates

An on/off signal: high while a key or step is held, low when it is not.

Gates say “now” and “for how long”. Keyboards and sequencers send a gate with every note; envelopes listen to it. In Kables a gate is anything above about 0.3.

Try it: Keyboard Step Sequencer Clock

LFO also: low-frequency oscillator

An oscillator too slow to hear, used to move other things automatically.

An LFO repeats a shape slowly, from many seconds per cycle up to a few cycles per second. Patched into pitch it gives vibrato, into a VCA tremolo, into a filter cutoff a slow sweep. Speed it up into the audio range and it becomes a sound source again.

Try it: LFO

Mixer also: mixers

Adds several signals together into one.

Mixers combine oscillators into one fat sound, or several modulators into one CV. In Kables every input also sums the cables plugged into it.

Try it: Mixer Stereo Mixer

Modular synth also: modular synthesizer, modular synthesis

A synthesizer split into separate modules that you connect yourself with patch cables.

Most synths have their signal path wired inside. A modular synth leaves it open: each module does one job (make a tone, filter it, shape its volume, move a knob for you), and nothing sounds until you connect the modules with cables. That freedom is what makes modular good for learning: every connection you make is an idea about sound you can hear.

Modulation also: modulate, modulating, modulator

Using one signal to change another over time.

Modulation is what makes a patch move: an LFO wobbling a filter, an envelope opening a VCA, a random voltage nudging pitch. The thing doing the moving is the modulator; the knob being moved is the destination.

Try it: LFO ADSR Sample & Hold Lorenz

Noise also: white noise, pink noise, brown noise

A random signal containing many frequencies at once: hiss, wind, surf, snares.

White noise is equally loud at every frequency; pink and brown get progressively darker. Filtered noise makes wind and percussion, and sampled noise makes random voltages.

Try it: Noise

Oscillator also: VCO, oscillators

A sound source that repeats a wave shape over and over, making a pitched tone.

A VCO (voltage-controlled oscillator) is the usual starting point of a patch. How fast the wave repeats is its frequency, which you hear as pitch. Its shape (sine, triangle, saw, square) is its waveform, which you hear as tone colour. An oscillator never stops on its own: you need a VCA and an envelope to make notes start and end.

Try it: VCO Wavetable

Patch also: patch cable, patching

A set of connections between modules, and the sound it makes.

To patch is to connect an output to an input with a cable. The whole arrangement of modules, cables and knob positions is also called a patch, which is why a saved sound is a “patch” rather than a preset.

Quantizer also: quantize, quantise

Snaps any pitch CV to the nearest note of a scale.

Random or smooth voltages played straight into an oscillator wander between notes. A quantizer rounds them to a scale, turning chaos into melody.

Try it: Quantizer

Resonance also: res

Boosts the frequencies right at a filter’s cutoff, adding a whistling, vocal peak.

A little resonance makes a filter sweep sound more pronounced. A lot makes the filter ring at its cutoff frequency, and at the extreme it can sing a tone of its own.

Try it: Filter

Sample & Hold also: S&H, sample and hold

Grabs the value of a signal on each trigger and holds it until the next one.

Fed with noise and clocked, a sample & hold produces a new random voltage on every beat: the classic computer-burble when patched to pitch or filter cutoff.

Try it: Sample & Hold

Sequencer also: step sequencer, sequencers

Plays a repeating pattern of notes or values, one step per clock pulse.

Each step holds a value (often a pitch) and a gate. Clock it, patch its pitch to a VCO and its gate to an envelope, and you have a melody that plays itself.

Try it: Step Sequencer Drum Seq Euclid Turing Machine

Slew also: glide, portamento, slew limiter

Smooths sudden jumps in a signal so it slides from one value to the next.

On pitch, slew gives portamento: notes glide into each other. On stepped random voltages it turns them into smooth, wandering curves.

Try it: Slew

Trigger also: triggers, trig

A very short pulse that means “go now”, with no length.

Triggers start things: a drum hit, a sample, a step of a sequencer. A clock is just a steady stream of triggers. Where a gate has a length, a trigger only has a moment.

Try it: Clock Drum Trio Burst

V/OCT also: 1V/oct, volt per octave, pitch CV

The pitch standard: each +1 on the input raises the pitch by one octave.

Volt-per-octave makes pitch control predictable: +1 is an octave up, +1/12 is a semitone. Keyboards, sequencers and quantizers send it; oscillators and filters with a V/OCT input follow it.

Try it: VCO Keyboard Quantizer

VCA also: voltage-controlled amplifier, amplifier

A volume control that another signal can turn up and down.

A VCA lets a signal through in proportion to its CV input. Feed it an envelope and a note fades in and out; feed it an LFO and you get tremolo; leave its CV empty and it stays shut. “Why is there no sound?” in a modular patch is very often an unopened VCA.

Try it: VCA

Waveform also: wave shape, sine wave, saw wave, sawtooth, square wave, triangle wave

The shape of one cycle of a wave, which decides how bright or hollow a tone sounds.

A sine is a single pure frequency. A triangle adds a few quiet harmonics. A sawtooth contains every harmonic and sounds buzzy and bright, which makes it ideal for filtering. A square contains only odd harmonics and sounds hollow or woody.

Try it: VCO