What Is a Synthesizer? The Complete Beginner’s Guide
If you’re getting started in music production, you might be wondering what a synthesizer is.
This guide will offer you an overview of how they work. We’ll delve into the most important details, but we’ll also keep it beginner friendly.
By the end, you should have a better understanding of how to make the most of them in your music.
Let’s dive in.
What is a synthesizer?
A synthesizer is a musical instrument that uses analog or digital signals to generate and process sound. Early synthesizers used analog electrical voltages as their sound source, while the most commonly-used synthesizers today are software plugins, which generate sound digitally.
Most synthesizers are played with a piano-style keyboard, but they’re also often played using sequencers, which we’ll explore more a bit later.
It’s also most common for synthesizers to be played in a standard Western chromatic scale, but many synthesizers now allow for other tuning systems.
There are multiple types of synthesis, each with different sonic characteristics and different design considerations.
This guide will focus on the fundamentals rather than cover every type of synthesizer out there.
Let’s start with an overview of the main components of synthesis.
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The basic structure of a synthesizer
Generally speaking, you can break down any synthesizer into these major components: sound sources, sound modifiers, and control sources.
- Sound sources are where the sound begins.
- Sound modifiers shape and process that sound through various changes.
- Control sources influence how and when those changes to the sound occur.
The most common type of sound source is an oscillator. It generates a raw audio tone—often a simple waveform like a square, sawtooth, or sine wave. On its own, this tone might sound static or plain, but it’s the foundation for everything that follows.
Once the sound is generated, it can be altered by modifiers. Two of the most important ones are filters (which change the frequency content of your sound source) and amplifiers (which change the volume of your sound source over time). We’ll explore both of these in depth a bit later.
Meanwhile, some of the most interesting aspects of synthesizers comes from how changes in your sound can be automated or influenced over time using control sources. A change being made to a parameter by a control source is often referred to as modulation.
The two most common forms of modulation are envelopes (which usually create changes in one non-repeating cycle per note) and LFOs (which create changes in repeating cycles). We’ll also cover these in more depth later.
For example, a common setup might use an oscillator to generate a harmonically rich sound. A filter can then tone down some of those harmonics to create a smoother texture. Meanwhile, an envelope can be used to make the sound start sharply and fade out gradually, while an LFO could be used to add a slow, repeating sweep to the tone’s brightness.
This technique of shaping a rich sound by gradually removing some of its higher-frequency content is known as subtractive synthesis.
Understanding these components gives you the foundation to explore how synthesizers create and transform sound. Next, we’ll dive deeper into each element to see exactly how they work and how you can use them creatively.
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What is an oscillator?
In synthesizers, an oscillator is a component that generates a self-repeating signal based on a mathematical waveform. Depending on how fast an oscillator repeats, it can be used either as a sound source or a control source.
The rate at which an oscillator repeats is called its frequency, which is expressed in Hertz (abbreviated as Hz). Frequencies can also be expressed in musical pitch or notes.
If an oscillator repeats at a rate within the range of human hearing (roughly 20 Hz to 20,000 Hz or 20 kHz), then it can be used as a sound source.
If it repeats at a rate below 20 Hz, it’s typically used as a control source, but audio-rate oscillators can be used as control sources too. We’ll explore that more a bit later.
For example, an oscillator repeating 261.1 times per second has a frequency of 261.1 Hertz, and this is expressed musically as Middle C.
In a synthesizer, you typically set the frequency of an oscillator with a few different parameters:
- Octave: Which octave range your oscillator occupies
- Coarse: Adjustment of frequency in larger units, usually semitones
- Fine: Adjustment of frequency in smaller units, usually in fractions of a semitone
An oscillator’s characteristics are influenced significantly by its waveform, and different waveforms produce different kinds of harmonic qualities.
Here are four of the most common waveforms and what they look like when visualized:
And here is how they sound (sine, sawtooth, square, and triangle):
Note that LANDR Synth X can scan continuously between major waveforms, giving you more flexibility and nuance in the tone of your patches.
Almost all waveforms have a fundamental pitch and additional harmonics that determine their overall sonic characteristics. A sine wave has no harmonics; it is just a fundamental tone.
The more harmonics a waveform has, the more rich and complex it is sonically. This often leads to sounds with more high-frequency information in them.
This is why a sawtooth wave sounds “brighter” than the sine wave. The sine wave has only a fundamental frequency and no additional harmonics.
Like we mentioned earlier, subtractive synthesis (which is one of the more common types of synthesis), is about shaping your oscillators’ sound by subtracting harmonics with filters.
However, other types of synthesis, like additive synthesis and FM synthesis, focus more on adding harmonics to create richer, more complex sounds.
We won’t go into every type of synthesis in depth, but we’ll give you a list of synthesis types at the end of this guide.
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LANDR Synth X is an example of what's called wavetable synthesis. We'll offer a quick definition of this near the end of the article, but this video will also give you an idea of why it's so powerful.
What are filters and amplifiers?
In synthesizers, a filter is a component that reduces or emphasizes specific frequency ranges in an oscillator or other incoming sound. Depending on the filter type and its parameters, different frequency ranges will be reduced or emphasized to create different effects.
Filters are most common in subtractive synthesis, but can be found in all kinds of synthesizers depending on the design choices of the manufacturer.
Amplifiers are the components in synthesizers that control the volume of sound sources. In a typical subtractive synthesizer, one or more oscillators will go through a filter and then reach an amplifier. The volume of the signal is then controlled by an envelope.
In many synthesizers, multiple oscillators can be configured and combined in a mixer, which is simply a type of amplifier that combines multiple input signals into a single output.
Let’s look at filters in a bit more detail. These are some of the most common parameters you can use to control how they work:
- Cutoff/Frequency: The value that determines which frequencies the filter will affect
- Resonance: The amount of emphasis that will be applied at the selected frequency value
- Key Tracking: The degree to which the frequency value corresponds to the note played on the keyboard
- Envelope/Contour Amount: The degree to which the frequency value is affected by an envelope
You’ll also typically be able to select between filter types. Three of the most common are:
- Low pass: Frequencies above the cutoff value are reduced
- Band pass: Frequencies outside a certain range around the cutoff value are reduced
- High pass: Frequencies below the cutoff value are reduced
Here’s how typical low pass, band pass, and high pass filter settings sound:
In all of those examples, some envelope control has been applied to the filter frequency value, which changes the frequency content over time.
Another envelope is controlling the amplifier to change the sound’s volume over time.
This brings us to our next stop — envelopes and their close relative, LFOs.
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What are envelopes and LFOs?
Read - Vintage Synth Plugins: The 8 Best VSTs for Classic Retro Sound
Envelopes are a type of component that controls the behavior of another component in a synthesizer, such as a filter or amplifier. They change your sound over time, usually each time a note is pressed. Their behavior can also respond to each time a note is released.
An envelope’s parameters determine how it changes the component that it’s assigned to. These four are the most common envelope parameters you’ll see:
- Attack: The time it takes for the sound to reach its maximum level after the note is triggered
- Decay: The time it takes for the sound to decrease from the maximum level to a sustained level
- Sustain: The level at which the sound holds while the note is sustained (held down)
- Release: The time it takes for the sound to fade away to silence after the note is released
Here’s a note played repeatedly with slight changes being made to the envelope.
In this example, the same envelope is being used to control both the filter frequency and the amplifier.
However, since many hardware and software synthesizers come with more than one envelope, you can assign one to the amplifier and one to the filter.
This can make for more nuanced results in your sound.
Envelopes typically do not repeat themselves without another note press (although many synthesizers allow you to configure looping envelopes).
This is where LFOs come in.
LFO stands for low frequency oscillator. In most synthesizers, LFOs are used to change various aspects of your sound over time in looping cycles, which can help you create a more dynamic sense of movement and variation.
Like the type of oscillators we explored earlier, LFOs output self-repeating waveforms, but they typically repeat at rates below the range of human hearing.
The waveforms you’ll find in the settings of an LFO are also often the same as the ones you’ll find in an audio-rate oscillator.
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How do you play a synthesizer?
To produce sound, most synthesizers need to be triggered by an external control signal. The most common tools for this are MIDI keyboards and sequencers — keyboards let you play notes manually, while sequencers automate note playback in loops.
Examples include the Arturia KeyStep and BeatStep. Hardware synths often have these built in, while software synths are controlled through external MIDI gear or your DAW’s sequencer.
A MIDI keyboard is a studio essential—not just for synths, but also for drums and samples.
Other key input signals include:
- Velocity: Affects loudness and dynamics according to how hard you press a key — also useful for modulating parameters like filter cutoff.
- Aftertouch: Adds expression based on pressure applied after pressing a key, useful for effects like vibrato.
- MIDI CC (Control Change): Lets you adjust synth parameters in real time using knobs or sliders.
Not all MIDI controllers support these features, so always check the specs to ensure compatibility with your needs.
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Monophonic vs. polyphonic synths
One of the most important specifications of a synthesizer is whether it is monophonic or polyphonic. Monophonic means that only one note can be played at a time, while polyphonic means that multiple notes can be played at a time. Polyphony is usually necessary to play chords on a synthesizer.
Because hardware synthesizers generally have more limitations in their circuit design or digital processing power, monophony and polypony are usually more important specifications in the hardware domain.
Most software synths, meanwhile, allow you to choose between monophonic and polyphony as you need, and many of them can allow for a high number of total simultaneous notes.
Eight notes of polyphony is typically plenty for being able to play chord progressions and melodies together.
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What is a modulation matrix?
Take a look at this overview of how modulation works.
A modulation matrix is the part of a synthesizer that allows you to route sources of control to destination parameters that change the characteristics of the sound you’re playing. You can, for instance, use a modulation matrix to route an LFO to the cutoff frequency of your filter, the frequency of an oscillator, or other parameters.
While not all synths have modulation matrices (and most have pre-configured routings for LFOs anyway), a synth that does have a mod matrix allows you to patch more advanced interactions between different parts of the synthesizer.
You could, for example, use a modulation matrix to route your amplifier envelope to the frequency of the LFO that is routed to your filter cutoff frequency.
Not only does this mean that your primary envelope is controlling both the volume of your notes over time, it’s also making the rate of change to your cutoff frequency faster at the beginning and slower at the end.
Here’s what this sounds like:
Note the settings in the modulation matrix in the upper right section of the synthesizer.
In a nutshell, this means you’re modulating your modulation, which is when synthesizer programming can get really interesting. All kinds of things are possible with a modulation matrix, from nuanced and subtle changes in your sounds to wild and experimental noises.
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The many types of synthesis
Synthesizers tend to be categorized based on the type of synthesis they specialize in. This is usually determined by what kind of sound source they use and other characteristics of the signal path.
Let’s run through some of the most important key terms that determine the type of synthesis you’re working with.
Analog synthesis uses continuous electrical signals and voltage-controlled components to shape waveforms generated by hardware oscillators. A modern example of this is the Arturia MiniBrute.
Analog modeling synthesis digitally emulates the behavior and sound characteristics of analog circuits and components. An example of this is the Korg microKORG2.
Wavetable synthesis generates sound by cycling through a table of pre-recorded waveforms, often allowing for dynamic timbral shifts. A software example of this is LANDR Synth X.
FM (frequency modulation) synthesis creates complex harmonic content by modulating one waveform with the frequency of another. A modern example of this is Native Instruments FM8.
Additive synthesis builds sounds by layering many sine waves of different frequencies and amplitudes to form a composite tone. An example of this is Madrona Labs Sumu.
Subtractive synthesis starts with harmonically rich waveforms and shapes the final sound by filtering out frequencies. A modern example of this is GForce AXXESS.
Physical modeling synthesis simulates the physical resonant modes of real-world objects to recreate the sound of percussive or acoustic materials. An example of this is AAS Chromaphone.
Granular synthesis breaks audio into tiny segments (grains) and rearranges or transforms them to produce new textures and time-based effects. An example of this is Ableton Granulator III.
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A world of synthesis awaits
Believe it or not, this article has only scratched the surface of what’s possible with synthesizers today.
To get more comfortable with how synthesis works, mess around with presets, and start programming your own patches, we definitely encourage you to get your hands on a simple yet powerful and well-designed software synthesizer like LANDR Synth. It comes with all subscriptions of LANDR Studio.
While synthesis might seem intimidating at first, it only takes a bit of time to get the hang of how it works, and it can get very addictive pretty fast. Before you know it, you’ll be making synthesis a major part of your music production workflow.
Happy synthing!
Devon Hansen is a producer, DJ, and writer with 20 years of experience in electronic music production. Having worked under various names and in a wide range of styles, Devon has performed several editions of MUTEK Montreal and has released music with labels in North America, the UK, and Japan. When not working on creative projects or playing tunes on Montreal’s n10.as radio, Devon can be found watching movies, cooking, and reading too much about gear.
@Devon HansenGear guides, tips, tutorials, inspiration and more—delivered weekly.
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