Synth Basics
A synthesizer can make almost any sound, from deep basses to glassy pads, but every synth is built from the same few building blocks. Learn them once and you can find your way around any synth, hardware or plugin.
What is a Synthesizer?
A synthesizer (or synth) is an instrument that creates sound electronically instead of by vibrating a string, a reed or a drum skin. You control the sound with knobs and sliders called parameters, and you play it with a keyboard or MIDI.
- Hardware synths are physical instruments, such as the Minimoog, the Roland Juno series or the Korg Minilogue.
- Software synths (soft synths) are plugins that run inside your DAW. They're cheaper, and you can open as many copies as your computer can handle.
A saved set of parameter values is called a patch or preset. Presets are a great starting point, but this module teaches you to understand and design your own.
Subtractive Synthesis
The most common type of synthesis is subtractive synthesis. You start with a sound that is rich in harmonics, then subtract (remove) some of them with a filter. It's like a sculptor starting with a block of stone and carving away what isn't needed. Robert Moog's synthesizers made this approach famous in the 1960s and 70s.
| Block | Job | You hear it as |
|---|---|---|
| Oscillator (VCO) | Generates the raw tone at a pitch | Pitch and basic timbre |
| Filter (VCF) | Removes some frequencies | Brightness or darkness |
| Amplifier (VCA) | Controls volume | Loudness, and how the note starts and ends |
| Envelope | Changes a setting once each time you press a key (Attack, Decay, Sustain, Release) | Plucky, slow, punchy or swelling notes |
| LFO | A slow, repeating wave that moves a setting up and down | Vibrato, wobble, tremolo |
The letters VCO, VCF and VCA come from analog synths: "voltage-controlled" oscillator, filter and amplifier. Using one control to move another is called modulation. A typical synth has at least one envelope wired to the amplifier, so the volume follows your key presses, and often a second envelope wired to the filter. You'll learn these in Envelopes (ADSR) and LFOs & Modulation.
Oscillators and Waveforms
An oscillator produces a repeating wave. The shape of the wave decides which harmonics it contains, and that decides its timbre. You met these waves in What is Sound?.
Waveforms and what they're used for
The sawtooth is the most-used starting point for subtractive synthesis, because it gives the filter the most harmonics to work with.
A pulse wave is a square wave with an adjustable pulse width. At 50% it's a square. Narrower widths sound thinner and more nasal. Slowly moving the width with an LFO is called pulse-width modulation (PWM) and gives a rich, chorus-like sound.
Tuning: Octave, Semitone and Fine
Most synths let you tune each oscillator in three steps:
| Control | Range (typical) | Use |
|---|---|---|
| Octave (or 32' / 16' / 8' / 4') | ±2 to ±4 octaves | Move the whole sound up or down; stack oscillators an octave apart for a fuller tone |
| Semitone (coarse) | ±12 to ±24 semitones | Tune an oscillator to an interval, such as +7 (a fifth) for a "power chord" lead |
| Fine (cents) | ±50 or ±100 cents | Small detuning for thickness. 100 cents = 1 semitone |
The foot markings (16', 8', 4') come from pipe organs: 8' is normal pitch, 16' is an octave lower, and 4' is an octave higher.
Detune and Unison
Detune means setting two oscillators slightly out of tune with each other, usually by 5–25 cents. The tiny pitch difference makes the waves drift in and out of phase. You hear a slow "beating" or shimmering movement, and the sound gets wider and fuller.
Unison takes this further. The synth stacks several copies of each voice (often 2–16), detunes them against each other, and usually spreads them across the stereo field.
- Low detune (5–10 cents): subtle thickness, still focused.
- Medium detune (10–25 cents): wide, lush, classic trance and EDM.
- High detune (25+ cents): out of tune and seasick, sometimes used for effect.
The famous supersaw sound is several detuned sawtooth waves in unison. It became widely known through the Roland JP-8000 in the late 1990s and is the core of trance leads and big EDM chords.
Heavy detune and unison on bass sounds can make the low end weak and unstable, because the detuned waves partly cancel each other, especially in mono. Keep the sub part of a bass in a single, un-detuned oscillator, and save unison for the higher layers. More in Panning & Stereo.
Noise
Most synths include a noise generator. Noise has no pitch; it contains random energy across the whole spectrum.
- White noise: equal energy at every frequency. Sounds bright and hissy.
- Pink noise: less energy in the highs. Sounds darker and more natural, like steady rain.
Mix a little noise into a sound to add "air" to pads, breath to flutes, or a sharp attack to plucks. Filtered noise with a fading envelope makes risers, sweeps, snares and hi-hats.
Voices, Mono vs Poly, and Glide
A voice is one complete note, with its own oscillators, filter and amplifier.
- Monophonic (mono): one note at a time. Pressing a new key cuts the old one. Ideal for basses and leads, because notes never overlap and muddy the sound.
- Polyphonic (poly): several notes at once, so you can play chords. Needed for pads, keys and chords. The polyphony number (for example 8 voices) is the most notes it can play at the same time.
Mono synths often have a legato mode: if you press a new key before releasing the old one, the envelope doesn't restart, so the line sounds smooth and connected.
Glide (portamento)
Glide, also called portamento, makes the pitch slide smoothly from one note to the next instead of jumping. The glide time sets how long the slide takes.
20–60 ms: a quick, subtle slide, good for funky basslines and leads.100–300 ms: an obvious swoop, like trap 808 slides or acid lines.- Longer: dramatic, sliding sci-fi effects.
Many synths offer "legato glide", which only slides when notes overlap. This lets you choose exactly which notes slide.
Popular Synths
You don't need expensive synths to make great sounds. The stock synth in your DAW can make most of the sounds in this module. Still, it helps to know the names you'll see in tutorials:
| Synth | Maker | Type | Known for |
|---|---|---|---|
| Serum | Xfer Records | Wavetable | Clear visual interface, huge in EDM and bass music |
| Vital | Vital Audio (Matt Tytel) | Wavetable | A powerful synth with a free version; similar workflow to Serum |
| Massive | Native Instruments | Wavetable | Defined many dubstep and electro basses of the 2000s and 2010s |
| Sylenth1 | LennarDigital | Virtual analog | Classic trance and house leads, light on CPU |
| Diva | u-he | Analog modeling | Very realistic analog sound, but heavy on CPU |
Stock synths worth learning first:
- Ableton Live: Wavetable, Analog, Operator, Drift.
- FL Studio: 3x Osc (very simple, great for learning), FLEX, Sytrus.
- Logic Pro: Retro Synth, ES2, Alchemy.
Wavetable, FM and other types of synthesis are covered in Synthesis Types.
Learn one synth deeply before buying another. Every subtractive synth has the same core blocks, so the skills transfer. A producer who knows one synth inside out will beat one who owns ten and knows none.
- Load your DAW's simplest synth [Ableton: Analog; FL Studio: 3x Osc; Logic: Retro Synth] and choose its default or "init" patch.
- Set oscillator 1 to sawtooth. Play a note and switch through every waveform to hear the difference.
- Turn on oscillator 2, set it to sawtooth, and detune it +12 cents. Then try +7 semitones and listen to the fifth.
- Set oscillator 2 back to 0 semitones and +12 cents, then set its octave to −1 for a fuller sound.
- Switch the synth to mono (voices = 1), turn on glide, and set the glide time to about 80 ms. Play a bassline with overlapping notes.
- Save the patch with a name like "My First Saw". You'll shape it with a filter in the next lesson.
In subtractive synthesis the signal flows from the oscillator to the to the amplifier.
One semitone is divided into cents.
The pitch slide between notes is called glide or .
1. What is the basic idea of subtractive synthesis?
- Adding sine waves together one by one
- Recording a real instrument and playing it back
- Starting with a harmonically rich wave and filtering some harmonics away
- Removing notes from a chord
Subtractive synthesis starts with bright waves like saws and squares and carves them with a filter.
2. Which waveform contains only the fundamental, with no harmonics?
- Sine
- Sawtooth
- Square
- Pulse
A sine wave is a single frequency, which is why it's used for clean sub bass.
3. What does detuning two oscillators by 10–20 cents do?
- Makes the sound an octave higher
- Turns the synth monophonic
- Removes all harmonics
- Makes the sound wider and fuller with gentle movement
The small pitch difference causes the waves to drift in and out of phase, creating thickness and shimmer.
4. Which kind of synth setting is best for chords and pads?
- Monophonic
- Polyphonic
- Legato
- Noise only
Polyphonic synths can play several notes at once. Mono synths play one note at a time.
5. Which of these synths has a free version?
- Diva
- Sylenth1
- Vital
- Massive
Vital is a wavetable synth with a free version, which makes it a popular first plugin synth.