A synthesizer, or synth, is an instrument that makes sound electronically instead of from a vibrating string, a drum skin or a column of air. It starts with a simple electrical wave, shapes it with filters and volume controls, and sends it to a speaker. Most synths are played with a keyboard, and they can sound like almost anything, from a deep bass to a glassy bell.
If you want to hear the synth in a song you like on its own, the Synth Remover can pull it out of the mix. This guide explains what a synthesizer is, how it works, and what the common kinds are.
A guitar makes sound when a string moves. A synthesizer makes sound by generating a signal inside the machine or inside a computer. Because that signal is made from scratch, you decide its pitch, brightness, loudness and how it changes over time.
That is why one synth can play a bass line, a lead melody, a soft background chord and a sound effect, all in the same song. It is also why a synth can imitate a flute or a string section, though it usually sounds a little different from the real thing.
Synths look complicated because of all the knobs. Most of those knobs belong to four basic parts.
- Oscillator. This makes the raw tone. You pick a wave shape, such as sine, triangle, square or sawtooth. A sine wave sounds smooth and pure. A sawtooth sounds buzzy and bright.
- Filter. This removes some of the high frequencies, or sometimes the low ones. Turning the filter down makes the sound darker and rounder. Turning it up makes it brighter.
- Envelope. This controls how the sound changes from the moment you press a key until it fades. The four stages are attack, decay, sustain and release. A short attack gives a pluck. A slow attack gives a pad that swells in.
- LFO. The name stands for low-frequency oscillator. It is a slow wave that moves another setting up and down, which makes vibrato, a wobble, or a sweeping filter.
Learn these four and you can understand the controls on almost any synth.
Main types of synthesizer
Synths are grouped by how they build the sound.
- Subtractive. Start with a bright, buzzy wave and cut away frequencies with a filter. This is the classic design and the easiest one to learn.
- Additive. Build the sound by stacking many sine waves, each at its own volume.
- FM (frequency modulation). One wave changes the pitch of another very fast, which makes bell-like and metallic tones.
- Wavetable. Move through a series of stored wave shapes, which gives sounds that change and evolve.
- Sample-based. Play back recordings of real instruments, stretched across the keyboard.
Synths also come as hardware (a box with knobs) or software (a plugin or app inside your music program). Software synths often cost less and let you save and recall every setting.
A monophonic synth plays one note at a time. That suits bass lines and lead melodies. A polyphonic synth plays several notes at once, so it can play chords. If you see a spec that says "8-voice," it means the synth can hold eight notes at the same time.
Synths run through pop, dance, hip-hop, rock, film scores and video game music. In a track they usually do one of these jobs:
- Bass. A low, steady line that carries the groove.
- Lead. The main melody, bright enough to sit above everything else.
- Pad. A soft, long chord that fills the background.
- Arpeggio. A chord played one note at a time in a repeating pattern.
- Effects. Risers and sweeps that build up to a big moment.
Because synths cover the whole pitch range, a single song may have five or six of them at once. That makes them hard to pick out by ear.
Many people learn synthesis by listening to one sound at a time. Here is how to do that with Unmix Studio:
- Open the Synth Remover and sign in with Google. New accounts get 5 free credits, with no card needed.
- Upload a song. MP3, WAV, M4A and FLAC work, up to 10 minutes.
- Press the big orange button. The price shows on the button first: most tools cost 1 credit per minute of song.
- When it finishes you get two reels, Synth and Without the synth. Click one to hear it alone, then download it as an MP3 at 320 kbps.
Splitting runs in the cloud, so there is nothing to install. For reference, in our own test a 4 minute 44 second song split into 6 stems in 56 seconds and cost 5 credits.
Expect a few mistakes. Synths often imitate other instruments, so an organ patch or a string pad can land in the wrong file. For those cases, the Organ Extractor may do better. If a lead or arpeggio is what you are after, a focused page and a couple of tries usually gets there.
Once you have the synth alone, you can turn the melody into MIDI notes. MIDI is a file of note data (which notes, when, how long) rather than sound. Drop the notes into your own synth and the same melody plays with any sound you choose.
Audio to MIDI is free, needs no sign-in and runs in your browser, so the file never leaves your computer. Choose Piano / keys for chords, or Vocals / humming for a single melody line. For more on splitting other instruments, browse the instrument tools.
Splitting someone else's song is fine for private learning. If you plan to release a track that uses a recording, you need permission from the rights holders.
It is an instrument that creates sound electronically. You choose a basic wave, shape it with a filter and a volume envelope, and play it, usually from a keyboard.
"Keyboard" describes the keys you press. A synth describes how the sound is made. A keyboard can play synth sounds, piano sounds or recorded samples, and a synth can be played from a keyboard, pads or a computer.
The basics are not hard. Learn the oscillator, filter, envelope and LFO on one simple synth, and the same ideas carry over to others.
You can try. Upload the song to the Synth Remover and you get a Synth file and a Without the synth file. Tightly mixed songs and sounds that imitate other instruments can leave some bleed.
It costs 1 credit per minute of song, and the price shows on the button before you run it. New accounts get 5 free credits, enough for one song up to 5 minutes. If processing fails, the credits go back to your account.