Intro to Synthesis

Foundations · The Classic Voice · Breaking the Paradigm

A synthesizer makes musical sound electronically. Subtractive synthesis starts with too many harmonics and takes some away, which is why this patch starts bright.

Timbre · Pitch · Rhythm

Osc A

Osc B

Detune 7 ct

A / B 50 · 50

Cutoff 2.9 kHz

Reso 2.0

Part 1 · Overview

Three Questions

Timbre

What does it sound like?

VCF · Envelope · LFO

Pitch

What note?

VCO · Sequencer · Keyboard

Rhythm

When does it happen?

Clock · Sequencer · Gate

Part 1 · Foundations

Voltage Basics

Amplitude / Level

How big the signal is. Measured in volts peak-to-peak.

Time / Frequency

How fast the signal repeats. 1Hz = one cycle per second.

Waveshape

The shape of the voltage change. Shape determines harmonic content.

Part 1 · Key Insight

CV = Audio

There is no electrical difference between an audio signal and a control signal.

They're all just voltages changing over time. The only difference is speed and intent.

Audio: fast - 20 Hz to 20 kHz
Control: slow - 0.1 Hz to ~30 Hz

Which is why, in modular, anything can control anything.

Part 1 · Timbre

Four Waveforms

Same fundamental pitch - different harmonic recipes - different timbre.

A single frequency, no overtones. Every other waveform is built from these.

Part 1 · Timbre · Pitch

Fundamentals & Overtones

A pitched sound is never one frequency. The lowest is the fundamental, the note you name it by. Every quieter tone above it is an overtone, sitting at a whole-number multiple of that frequency.

Time Domain

Spectral View (hover a bar)

Overtones Fundamental

Rolloff 1/n

Fundamental:

Include:

The fundamental - a single frequency. The note you hear as "the pitch."

Part 1 · Timbre

The Filter

The VCF removes frequencies from a signal. Cutoff sets where; resonance emphasizes the edge.

dB/oct

Cutoff 2.0 kHz

Resonance 1.0

Sweep the cutoff to hear harmonics disappear. Crank resonance to hear the filter sing.

Part 1 · Pitch

Pitch & Frequency

Pitch is frequency. 440 Hz = A4. Double the frequency = up one octave. Halve it = down one octave.

A4 440.0 Hz

Freq

Part 1 · Pitch

Noise

Noise has no pitch. It is every frequency at once. Filter it and you get rumble, hiss, wind, surf.

Filter 15.0 kHz

White noise: equal energy at every frequency.

Part 1 · Pitch

1 Volt per Octave

Analog and modular synths use voltage to control pitch. The standard: each additional volt doubles the frequency, up one octave.

The tune knob sets the base pitch at 0V. Every +1V is an octave up, every semitone 1/12V (~0.083V).

Base note C2

1V/oct is the standard that lets modules from different makers talk to each other.

Part 1 · Pitch

Controlling Pitch

Keyboard

Discrete notes. Each key sends a voltage. The Minimoog way.

Sequencer

Programmed pattern, looping. Same machine, three lists of voltages. Click any cell to write your own.

Sample & Hold

Grabs a random voltage on each clock tick. Quantize snaps those voltages to C major.

Part 1 · Rhythm

Gates & Triggers

A gate is a voltage that stays high as long as a key is held. A trigger is a brief pulse - just a click to say "now."

Gate: on while held, off on release
Trigger: short pulse (~1-10 ms)

Hold the gate to hear the raw on/off. Tap trigger for a short pulse.

A gate turns sound on and off - but real instruments don't work that way.

Part 1 · Rhythm

Envelopes

An envelope shapes how a value changes over the life of a note.

Attack 50ms

Decay 200ms

Sustain 60%

Release 400ms

Press to trigger the envelope. Hold for sustain, release to hear the release stage.

Part 1 · Dynamics

The VCA

A Voltage Controlled Amplifier is a volume knob other modules can turn.

The envelope makes a shape. The VCA applies it.

Level 75%

Control:

Without one, the oscillator just drones.

Part 1 · Modulation

The LFO

A Low Frequency Oscillator is too slow to hear, but it can wiggle any parameter: pitch (vibrato), filter (wah), amplitude (tremolo).

Rate 5.0 Hz

Depth 50%

Target:

Part 1 · Modulation

Envelope as Modulation

An envelope fires once per note - it shapes a gesture. Route it to different targets to hear the difference.

Target:

Attack 80ms

Decay 600ms

Envelope sweeps filter cutoff - brightness rises and falls with each trigger.

In modular, an envelope can go anywhere.

Part 2 · Signal Path

Building the Classic Voice

Released in 1970, the Minimoog defined the architecture of the synthesizer. Nearly every synth since follows this template.

We'll build this signal path one block at a time, then break it apart to see what modular makes possible.

One signal path, no patch cables, and no say in the order.

Part 2 · Build

Build the Voice

Step 1 of 7

Oscillator

One oscillator straight to the output.

After Today

Next Steps

Start for free

Download VCV Rack. Same software we used today, and it costs nothing.

Befaco, Mutable Instruments, 4ms, ALM/Busy Circuits, Bastl and Erica Synths all have official modules in the library, free or cheap. Try the hardware before you buy it.

Try my SignalFunctionSet modules while you are in there.

vcvrack.com

Borrow the hardware

Join Synth Library and take gear home. On the shelf right now:

Moog Mother-32
Instruo Seashell
Korg Monologue
Make Noise 0-Coast
Pittsburgh Modular (various)

synthlibraryportland.org

Read a book

Welsh's Synthesizer Cookbook, Fred Welsh. Patch recipes for specific sounds.

Electronic Music: Systems, Techniques, and Controls, Allen Strange. The classic text.

Omri Cohen's cookbooks. VCV specific and current.