Intro to Synthesis

Foundations · The Classic Voice · Breaking the Paradigm

Timbre · Pitch · Rhythm

Part 1 · Overview

What is Synthesis?

Synthesis means building sound from scratch using electrical signals.

In this workshop we focus on subtractive synthesis - start with a harmonically rich signal and sculpt it by removing what you don't want.

Think of a sculptor starting with a block of marble. The raw oscillator is the block. The filter is the chisel.

Start full. Carve away. Shape what remains.

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

This is what makes modular synthesis powerful: anything can control anything.

Part 1 · Timbre

Four Waveforms

Same fundamental pitch - different harmonic recipes - different timbre.

A single frequency. No overtones. The purest possible tone - the building block of all other waveforms.

Part 1 · Timbre · Pitch

Fundamentals & Overtones

Time Domain

Spectral View

Overtones Fundamental

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 - all frequencies at once. Filter it and patterns emerge: rumble, hiss, wind, surf.

Filter 15.0 kHz

White noise: equal energy at every frequency - pure randomness.

Part 1 · Pitch

1 Volt per Octave

Most synthesizers use voltage to control pitch. The standard: each additional volt doubles the frequency, up one octave.

The oscillator's tune knob sets the base pitch at 0V. From there, every +1V is one octave up. Every semitone is 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. Each step sends a pitch CV in a loop.

Sample & Hold

Grabs a random voltage on each clock tick. Generative melodies.

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 scales one signal by another. It's a volume knob that other modules can turn.

The envelope generates a shape - the VCA applies it. Without a VCA, there's no way to start and stop notes.

Level 75%

Control:

The VCA is the invisible instrument - it turns voltage into expression.

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 recreate this signal path in VCV Rack, then break it apart to explore what modular makes possible.

First: the fixed path. Then: what happens when you remove the limits.

Part 3 · Modular

Breaking the Paradigm

Modular

Timbre

FM, ring mod, waveshaping, self-oscillating filters

.

Pitch

Sequencers, LFOs, noise, other oscillators

.

Rhythm

Clocks, dividers, generative feedback loops