Synthesis Essentials

Synthesis can look intimidating when every control has a new name, but most patches are built from a small set of ideas: create a sound, shape its tone, shape its volume, and add movement. This guide gives you a practical foundation you can use in almost any synthesizer.

Start with the three parts of sound

A sound begins as vibration. In air, that vibration creates changing pressure that reaches our ears. When you work with a synthesizer, three qualities are especially useful:

• Frequency is how quickly a waveform repeats. We usually hear its fundamental frequency as pitch.
• Amplitude describes the strength of the waveform and strongly influences perceived loudness.
• Timbre is the character or colour of a sound. It is shaped by the balance of frequencies, the way the sound changes over time, and details such as noise or inharmonic content.

Oscillators: the raw material

An oscillator produces a repeating waveform. Different shapes contain different combinations of a fundamental tone and harmonics, which is why they sound different even when they play the same note.

The classic subtractive signal path

Many synthesizers follow the same left-to-right idea. You begin with a harmonically rich sound, then remove and shape parts of it.

• The oscillator creates the raw waveform.
• The mixer balances multiple oscillators or noise sources.
• The filter emphasizes or removes parts of the frequency spectrum. A low-pass filter, for example, lets lower frequencies through while reducing higher ones.
• The amplifier controls the final level of the sound.

Envelopes shape each note

An envelope describes how a parameter changes after you press and release a note. The familiar ADSR envelope has four stages:

1. Attack: how long it takes to reach the peak.
2. Decay: how long it takes to move from the peak to the sustain level.
3. Sustain: the level held while the note remains pressed.
4. Release: how long it takes to return to zero after the note is released.

Apply an envelope to amplitude for the overall shape of the note, or route one to filter cutoff, pitch, or another destination to change the tone over time.

LFOs add repeating movement

A low-frequency oscillator is usually too slow to hear as a separate pitch. Instead, it repeatedly moves another parameter. Route it gently to pitch for vibrato, amplitude for tremolo, filter cutoff for a pulsing tone, or wavetable position for evolving colour. Small amounts often sound more intentional than extreme modulation.

Four synthesis methods worth recognizing

• Subtractive synthesis starts with a harmonically rich waveform and shapes it with filters and amplifiers.
• Additive synthesis builds a complex sound by combining simpler sine-wave partials.
• FM synthesis uses one oscillator to modulate the frequency of another, producing new harmonic or inharmonic sidebands.
• Wavetable synthesis scans through a collection of waveforms, making it easy to create changing timbres.

Sampling is another major approach: instead of generating the source with an oscillator, a recorded sound becomes the raw material.

Putting this into practice with Ableton Operator

Operator combines FM, additive, and subtractive synthesis. Its four oscillators can be routed in different algorithms: some arrangements let oscillators modulate one another, while others allow them to sound in parallel. Operator also includes a filter, an LFO, a pitch envelope, a filter envelope, and a dedicated envelope for each oscillator.

A reliable way to learn sound design

Change one control at a time, listen carefully, and return it to its starting point before moving on. Begin with a simple patch instead of a finished preset. If you can predict what a control will do before you move it, the instrument is becoming part of your musical vocabulary.

Remember: oscillator, filter, amplifier, envelope, and modulation. Learn those five ideas and unfamiliar synthesizers become much easier to understand.