In this guide
A synthesizer creates and shapes electronic sound. In a common subtractive synth, an oscillator supplies a tone, a filter changes its frequency content, and an envelope controls how a parameter changes over time. Different synths use different sound-generation methods.
A synthesizer is an electronic instrument that creates and shapes sound. It can produce basses, leads, pads, percussion or sound effects. Some synthesizers are physical instruments with keys and knobs; others are software instruments played in a music app or DAW.
Instead of beginning with one fixed recording, a common synth lets you choose a sound source and change its tone and behavior. A bright oscillator, a filter and an envelope can become a short pluck or a slowly swelling pad. Not every synth uses the same methods, so its controls and results depend on its design.
How does a synthesizer work?
A useful starting model is subtractive synthesis: generate a harmonically rich sound, reduce some frequencies with a filter, and shape how it changes over time. The following parts are common in this design, but they are not universal requirements for every synthesizer.
| Part | What it does | What to listen for |
|---|---|---|
| Oscillator | Generates a repeating signal that can create a pitched tone. | Compare the character of available waveforms at the same pitch. |
| Filter | Changes the balance of frequencies in a signal. | Lowering a low-pass cutoff often makes a bright sound darker. |
| Amplifier and envelope | Control the signal level and how it evolves over a note. | A longer attack makes the sound fade in more gradually. |
| LFO | Provides a repeating modulation signal that can change another control. | A gentle pitch modulation can create vibrato. |
Ableton’s interactive synthesis lessons demonstrate oscillators, filters, envelopes and modulation. For a physical example, the Moog Werkstatt manual explains its audio and control paths.
Make a simple first sound
Use a subtractive software synth or hardware synth with an oscillator, low-pass filter and amplitude envelope. The labels may differ. Start with your device volume low, load an initialized patch if available, and hold one note while making small changes.
- Choose one oscillator. Select a sawtooth waveform if available. Play a comfortable note and set a moderate output level.
- Move the filter cutoff. With a low-pass filter selected, slowly lower the cutoff and listen as the sound becomes less bright. Raise it again; keep resonance modest while learning.
- Shape the start. Increase the amplitude envelope’s attack and play a new note. The sound should rise more slowly. Return to a short attack for a more immediate start.
- Shape the end. Increase release, play and let go. The sound should fade for longer after release. Set a short release if you want a tighter sound.
- Compare and save. Change one setting at a time, compare it with the starting patch, and save a preset or project when you like the result. Record a short MIDI part and render audio if you want to share the sound.
An envelope may also control a filter, pitch or another parameter. Its attack, decay, sustain and release settings describe a control shape; they do not always change volume. See Ableton’s envelope explanation.
What is the difference between a synthesizer, sampler and MIDI controller?
| Device or concept | Main job | Example |
|---|---|---|
| Synthesizer | Generates and shapes sound using its available synthesis methods. | A software synth creates a bass tone from an oscillator. |
| Sampler | Plays and may reshape recorded audio. | A sampler plays a recorded glass tap from a keyboard. |
| MIDI controller | Sends performance instructions such as notes and controls. | A keyboard sends notes to a software synth; some controllers have no built-in sound engine. |
These categories can overlap: some instruments combine samples with synthesis, and some keyboards include both keys and a sound engine. Read how a sampler works and what MIDI does for the distinction between recorded sound and performance data.
Hardware vs. software synthesizers
A hardware synth provides a physical instrument and controls; depending on its design, it may need a separate audio connection to speakers, an interface or a mixer. A software synth runs on a computer or other compatible device and may be available as a standalone application, a plugin or both. A plugin requires a compatible host; check VST plugin compatibility before installing.
Neither category guarantees a particular sound or workflow. When comparing an instrument, check its sound engine, number of simultaneous voices, audio and MIDI connections, supported operating system, licensing and whether it includes the controls you want to learn.
Analog, digital and other synthesis methods
Analog synthesizers use analog circuitry in their sound path; digital synths use digital processing. A hardware instrument can be digital, and a software instrument may model analog behavior. Subtractive synthesis is one approach, not the definition of synthesis: other approaches include frequency modulation and additive synthesis. The sound of any specific instrument depends on its implementation and settings.
For a simple listening reference, the tone generator creates a sine-wave WAV locally. It does not play MIDI, offer synth modulation or create a complete synthesizer patch. Start at low playback volume and do not treat it as a calibrated hearing test.
Common questions
Is a synthesizer a keyboard?
Some have built-in keys, but others are modules or software instruments controlled by an external keyboard, sequencer or on-screen notes.
Do I need music theory to use a synth?
No. You can begin by playing one note and listening to how the controls change it. Theory becomes useful when composing melodies and chords.
Can a synthesizer sound like a real instrument?
It can imitate aspects of acoustic instruments, but the result depends on the instrument and programming. Sample-based instruments use recordings, while synthesis generates or transforms sound through other methods.