What Is a Synthesizer? How Synths Work and Where to Start
For Artists
A synthesizer is an electronic instrument that generates sound instead of recording it. Many synthesizers start with a raw tone from an oscillator, a stored sample, or a mathematical algorithm, then shape it with some combination of filters, amplifiers, and modulation. The result can imitate a piano or a string section, or produce sounds no acoustic instrument can make.
Ask "what is a synthesizer" and you get two kinds of answer. The gear answer lists brands and knobs. The useful answer explains what happens between pressing a key and hearing a sound, because that chain is the same on a 1970 Minimoog, a free plugin, and a wall of modular cables. Once you can hear each stage doing its job, every synth becomes readable.
This guide walks the chain from oscillator to output, sorts the main synth types with one landmark instrument each, and settles the confusion between a synthesizer, a MIDI keyboard, and a sampler. It ends with a starting path from $0 to $500. If you are building a production setup from the ground up, Music Production Basics covers where a synth sits in the wider workflow.
How a Synthesizer Makes Sound
Almost every synth, hardware or software, follows the same path. A key, pad, sequencer, or DAW can send a note event or control signals: MIDI Note On carries note number and velocity, while analog setups may use separate pitch control-voltage and gate or trigger signals. The signal then moves through three stages before it reaches your speakers.
Read the flow like a diagram, left to right:
Note event (key or MIDI note) → Oscillator (makes the raw tone) → Filter (removes frequencies) → Amplifier (sets the level over time) → Output. Sitting above that line are the modulators, envelopes and LFOs, which get patched down into any stage to move it automatically.
The oscillator is the sound source. On an analog synth it is a circuit producing a repeating voltage; on a digital synth it is a waveform, a wavetable, or a sample being read from memory. On its own an oscillator sounds like a raw buzz or beep held at one volume forever, which is why nobody stops there.
The filter is where the buzz becomes an instrument. A low-pass filter lets low frequencies through and removes the highs, so the same sawtooth wave can read as a bright brass stab or a dark, muffled pad depending on where the cutoff sits. A filter mainly attenuates parts of the spectrum, while resonance can emphasize frequencies near the cutoff. It sculpts what the oscillator already produced.
The amplifier controls loudness, and it almost never sits at a fixed level. An envelope tells it how quickly to open when a note starts and how quickly to close when the note ends, which is the difference between a pluck and a swell. This oscillator, filter, amplifier order is called subtractive synthesis, and Subtractive Synthesis Explained goes stage by stage with waveform and envelope tables if you want the full parameter tour.
What You Hear Change at Each Stage
Knowing the names of the stages is not the same as hearing them. The fastest way to learn a synth is to load an init patch (one plain oscillator, filter wide open) and turn one control at a time while a note is held. This table is what to listen for.
Stage | The control you turn | What you hear change | Sound it tends to make |
|---|---|---|---|
Oscillator | Waveform selector | The basic character: sawtooth is buzzy and bright, square is hollow, sine is pure and soft | The raw material for everything else |
Oscillator | Detune between two oscillators | A single tone turns thick and wide as the two drift against each other | Big pads, wide leads, supersaws |
Filter | Cutoff | Brightness. Sweep it down and the sound goes dull and distant; sweep it up and the edge returns | Warm basses, muffled pads, opening sweeps |
Filter | Resonance | A whistle or peak appears right at the cutoff, and the sweep starts to sing | Acid lines, squelchy basses |
Amplifier | Envelope attack | Whether the note hits instantly or fades in | Plucks and stabs (fast), swells and pads (slow) |
Amplifier | Envelope release | Whether the note stops dead or trails off after you let go | Tight bass (short), washy pads (long) |
Modulation | LFO to pitch | A wobble in tuning, slow or fast | Vibrato |
Modulation | LFO to filter cutoff | A rhythmic opening and closing of brightness | Wobble bass, pulsing pads |
Modulation | Velocity to filter or amp | Harder key hits come out louder or brighter | Expressive, playable patches |
Two things follow from this table. First, most of what people call "the sound" of a synth lives in the filter and the amplifier envelope, not the oscillator, which is why two different synths with the same waveform can sound nothing alike. Second, modulation is what separates a static tone from a sound that feels played, and a vocoder is one dramatic example: your voice becomes the modulator that shapes the synth.
Types of Synthesizers
"Synthesizer" covers several ways of generating that raw tone. The signal path stays similar; the sound source and the way it gets shaped differ. One landmark instrument per type tells you what the type sounds like at its best.
Type | How it makes sound | Landmark example | Known for |
|---|---|---|---|
Analog | Voltage-controlled circuits generate and filter the waveform | Minimoog Model D (Moog, 1970) | Fat basses and leads, slight drift and warmth |
Digital (sample-based) | Plays short recorded samples through synth-style filters and envelopes | Korg M1 (1988) | The piano and organ presets heard across 1990s house |
FM | One oscillator modulates the frequency of another, producing complex harmonics | Yamaha DX7 (1983) | Electric pianos, bells, and the glassy keys of 1980s pop |
Wavetable | Scans through a table of stored single-cycle waveforms, morphing between them | PPG Wave (early 1980s); Xfer Serum (2014) is the common modern reference | Evolving textures, modern bass design |
Modular | Separate modules (oscillators, filters, envelopes) connected by patch cables | Moog's 1960s modular systems; today mostly Eurorack, a format Doepfer introduced in 1995 | Total flexibility, generative and experimental patches |
Software | Any of the above, running as a plugin inside your DAW | Native Instruments Massive (2007) | The wobble basses of late-2000s dubstep and electro |
The rows blur at the edges. Virtual analog synths are digital instruments that model analog circuits, so a modern "analog-sounding" plugin belongs in the software row rather than the analog one. Many hardware synths sold today are hybrids too: digital oscillators through an analog filter, or analog oscillators with digital effects and preset memory.
If you have heard the pads and arpeggiated basslines of synthwave, you have heard producers chasing the analog row on purpose, usually with software that models it.
Synthesizer vs MIDI Keyboard vs Sampler
This is the question hiding under most "what is a synthesizer" searches, because all three can look like a keyboard with knobs. The difference is where the sound comes from.
Synthesizer | MIDI keyboard (controller) | Sampler | |
|---|---|---|---|
Makes its own sound? | Yes | Usually no. Most send note data only, though some models carry sounds | Yes, by playing back recordings |
Where the sound comes from | An oscillator, algorithm, or stored waveform, typically shaped by filters and envelopes | The software instrument or hardware it is connected to | Audio you recorded or loaded, mapped across the keys |
Play a note an octave higher and you get | The same tone regenerated at the new pitch | Whatever the connected instrument does | The recording played back faster, unless the sampler stretches it |
Needs a computer? | No for hardware, yes for plugins | Yes, or an external sound module | No for hardware units, yes for plugins |
Classic example | Minimoog, DX7 | A 25- to 88-key controller with no speaker | Akai MPC, E-mu Emulator |
A MIDI keyboard is a remote control. It sends note number, velocity, and timing as MIDI data, and the synth or plugin at the other end turns that data into sound. A synth with keys is both things at once: a controller bolted to a sound engine, which is why most hardware synths also send MIDI to your DAW.
A sampler does not generate a tone. It plays back a recording, and sampling is the craft of choosing and cutting that recording. The line blurs because modern samplers run the audio through the same filters and envelopes a synth uses, and sample-based synths like the Korg M1 start from recordings too. The practical test: if you can change the fundamental waveform, it is behaving as a synth; if you can load your own audio, it is behaving as a sampler.
Where to Start: $0 to $500
You do not need hardware to learn synthesis, and buying it first is the most common way to stall. Prices below are typical street prices as of 2026 and move often, so treat the tiers as a shape, not a quote.
Budget | What to get | Why this step |
|---|---|---|
$0 | The stock synths in your DAW (Retro Synth in Logic, Analog or Wavetable in Ableton Live, 3x Osc in FL Studio, edition permitting) plus free plugins such as Surge XT, Dexed, and Vital's free tier | Every concept in this guide is here already. Learn one synth's init patch until you can build a bass, a pad, and a lead from nothing |
Under $150 | A 25- or 49-key MIDI controller | Playing a patch teaches velocity and envelope response in a way clicking notes into a piano roll never will |
$100 to $300 | A compact hardware synth such as Korg's Volca line or Behringer's small analog units | Hands on knobs, no screen, one signal path. Hardware forces you to hear each stage instead of reading it |
$300 to $500 | A self-contained synth such as the Arturia MicroFreak | Preset memory, an integrated playing surface, and enough depth to write and perform with for years |
The order matters more than the budget. Spend the $0 tier first, and stay there until the table in the "what you hear" section is something you can reproduce by ear. Move to a controller when you catch yourself wanting to play a part rather than draw it. Buy hardware only when you can name the type you want (analog for basses and leads, FM for keys and bells, wavetable for evolving textures) because that choice, not the price, decides whether the box gets used.
If you write and produce your own music, this is also where artists managing their own production tend to over-buy. A $500 synth you understand will outlast a $2,000 one you browse presets on.
Frequently Asked Questions
Is a keyboard the same as a synthesizer?
No. A keyboard is an interface. A synthesizer is a sound engine that generates and shapes tones, and it may have keys, pads, or none at all. Many home keyboards play back samples rather than synthesizing.
Do I need a hardware synth to make electronic music?
No. Every major DAW includes software synths that use the same oscillator, filter, and amplifier chain as hardware. Hardware adds hands-on control and a fixed signal path, which helps some people learn faster.
What is the difference between a synthesizer and a sampler?
A synthesizer generates its tone from an oscillator or algorithm. A sampler plays back a recording mapped across the keys. Many modern instruments do both, running samples through synth-style filters and envelopes.
What was the first synthesizer?
Electronic instruments go back more than a century, but the modular systems Robert Moog and Don Buchla built in the 1960s defined the synthesizer as we know it. The 1970 Minimoog made it portable and playable.
Read Next
Once the patches turn into finished tracks, How to Plan a Music Release: Step-by-Step Checklist is the next step when you are ready to put them in front of listeners.