How Do Synthesizers Work? Ultimate Guide to Using Synths

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Since their introduction, they have inspired countless genres of electronic music and found their way into pop music, film scores, and experimental soundscapes.

The word synthesizer traces back to the mid-20th century, describing devices designed to generate sound electronically.

Early synthesizers were large, often expensive machines that filled entire rooms. The earliest models appeared in academic and research settings before making their way into commercial music stores.

As technology advanced, synthesizer companies refined their designs, creating smaller, more accessible products for musicians looking to explore new sonic territories.

Understanding the basics

Sound waves and frequencies

Synthesizers work by manipulating fundamental building blocks of audio, namely sound waves. A sound wave is a vibration travelling through air, measured by its frequency in Hertz (Hz).

The fundamental frequency of a note determines its pitch, while the waveform’s harmonic content shapes its unique sound and timbre.

In acoustic instruments, these vibrations happen through strings, membranes, or air columns. However, electronic musical instruments like synthesizers generate sound using electronic circuits or digital signal processing.

This approach allows you to create sounds that differ significantly from those found in nature.

Main types of synthesizers

Analogue synths vs. digital synths

One of the fundamental distinctions in the world of synthesizers is the difference between analogue synths and digital synths.

An analogue synthesizer uses continuous electrical signals to generate sound, often resulting in a warm, organic character.

These synths use components like transistors and capacitors, which introduce characteristic behaviors and subtle variations in the signal path.

Digital synthesizers use digital signal processing and algorithms to generate and process tones, offering precise control and advanced manipulation capabilities. Modern digital synths can also accurately model analog circuit behavior, including component-level interactions and characteristics

While there are sonic differences between analog and digital synthesis, the perceived qualities like ‘warmth’ are highly dependent on specific implementation, design choices, and individual preference.

Today, modern digital synths can accurately model analog circuit behaviour (including component-level interactions and characteristics). They’ve got so advanced, in fact, that many synth aficionados have been fooled by blind tests. There may be hardcore analogue purists out there who can, but it’s clear the average listener would struggle to discern any difference (nor care most likely!).

Ultimately, the great benefit to digital synthesizers is their expansive the sonic palette, allowing for complex waveforms, sampling features, and integrated effects that push beyond traditional sound design limits.

Modular synthesizers

Modular synthesizer represent the most customisable form of these electronic instruments.

A modular system is composed of separate units—oscillators, filters, envelopes, and more—that the user patches together manually with cables.

This physical approach to controlling synthesizers allows for a mind-boggling variety of sonic possibilities, as every connection can alter the signal path in a unique way.

Musicians who opt for modular synths can build their own systems over time. By choosing modules from different synthesizer companies, they create a personalised instrument to match their musical goals.

This flexibility often comes at the cost of portability and complexity, but the sounds produced can be genuinely one-of-a-kind.

Polyphonic synthesizers

Oberheim 4voice, famously used by Depeche Mode and John Carpenter

Another vital category is the polyphonic synthesizer, which refers to any synth capable of playing multiple notes simultaneously. Traditional monophonic synths can only play one note at a time, making them well-suited for bass lines and solos.

In contrast, polyphonic synths allow you to perform chords and complex harmonies, broadening your compositional potential.

A polyphonic synth typically uses several oscillators and amplifier stages in parallel. Each note is treated as its own audio signal path, so you can sustain multiple pitches.

Many polyphonic synthesizers also feature advanced modulation and layering options, letting you craft dense, evolving textures.

Methods of audio synthesis

Subtractive synthesis

The most common approach in audio synthesis is subtractive synthesis, which is the hallmark of many classic synthesizers like the Moog synthesizer.

Subtractive synthesizers start by generating rich waveforms such as a sawtooth wave or a square wave.

These waves have abundant harmonic content, making them ideal for sculpting into different sound textures.

Once the raw wave is generated, filters are used to remove or attenuate specific frequencies. This “subtracting” process sculpts the waveform, shaping the final sound.

In addition to filtering, envelopes allow control over attack decay sustain parameters, letting you determine how quickly the sound reaches its peak, how it transitions, and how it fades away.

Through this workflow, you can achieve anything from gentle pads to aggressive leads and punchy basses.

Additive synthesis

In contrast to subtractive techniques, additive synthesis builds sounds by layering simple waveforms—often sine waves—together.

Each sine wave may represent a harmonic or partial of the overall tone. You can create rich, complex sounds from the ground up by summing multiple waves at varying amplitudes and frequencies.

Additive synthesis grants a high level of control over the harmonic structure, enabling the design of unique sound profiles that might be difficult to achieve with subtractive methods.

Although it demands more computing power in the digital realm, additive processes can offer unparalleled precision in shaping the sound generated.

Frequency modulation (FM) synthesis

Frequency modulation (FM) involves using one oscillator (the modulator) to modulate the frequency of another oscillator (the carrier).

The ratio between carrier and modulator frequencies, along with the modulation index, determines the harmonic sidebands produced. This interaction creates complex spectra ranging from bell-like tones to metallic textures

FM synthesis gained significant traction in the 1980s, popularised by the legendary synths like the Yamaha DX7, capable of producing distinctive bell-like and electric piano tones.

Unlike subtractive or additive methods, FM relies on the dynamic interaction between carrier and modulator frequencies.

Subtle variations in modulation depth and frequency can lead to dramatic shifts in timbre.

As a result, FM is well-suited for crafting evolving, complex sounds that can change character based on how the modulation is set.

Key components of synthesizers

Oscillators (VCO, DCO)

At the heart of most synthesizers are oscillators, which are responsible for producing the basic waveform. In analogue synths, these are often referred to as voltage-controlled oscillators (VCOs), while in digital models, you might find digitally controlled oscillators (DCOs).

Both types serve the same purpose—creating a continuous, repeating waveform such as a sine wave, sawtooth wave, pulse wave, or square wave.

Oscillators usually have different wave shapes available, each with its own harmonic content. By selecting or blending multiple wave shapes, you establish the foundation of your raw sound.

Advanced synthesizers may include multiple oscillators that can be layered, detuned, or modulated to form richer timbres.

Filters and envelopes

Filters shape the spectrum of an oscillator’s output, making them an essential part of audio synthesis. A low-pass filter, for example, allows only frequencies below a certain cutoff point to pass, effectively removing higher harmonics.

A high-pass filter does the opposite, removing lower frequencies, and a band-pass filter isolates a specific frequency range.

These various filter types let you sculpt the sound created in nuanced ways, emphasising or suppressing different portions of the harmonic content.

Envelopes further refine the final sound by controlling how a tone evolves.

Typically defined by four stages—attack decay sustain and release—envelopes dictate how quickly a note reaches full volume, how quickly it falls to a sustained level, how long it stays there, and how it fades away.

Mastering the ADSR envelope is crucial for shaping expressive synth sounds.

Low frequency oscillators (LFOs)

A low-frequency oscillator (LFO) is typically used to modulate parameters at sub-audio frequencies, though some synths allow LFOs to operate at audio rates for more complex modulation effects.

Instead of generating a tone that you can hear, it produces a slowly varying signal used to modulate other parameters.

For instance, you can route an LFO to control pitch, filter cutoff, or amplitude. When set at a slow rate, this can create vibrato, tremolo, or sweeping filter effects.

LFOs add motion and character to a patch, making static tones feel alive. By adjusting the LFO’s waveform, rate, and depth, you can tailor the modulation to your music’s vibe, whether that’s a gentle pulse or an aggressive wobble.

For those seeking a different sound from typical acoustic instruments, LFOs offer a straightforward way to incorporate dynamic movement into their own sounds.

Software vs. hardware synths

Today, musicians can choose between hardware synths and software synthesizers (often called software synths). Hardware synths are physical units with dedicated circuitry, knobs, and sliders.

They frequently offer a tactile experience that many find inspiring, and they don’t tax your computer’s processing power.

By contrast, software instruments run within a digital audio workstation (DAW) or as standalone programs. Modern software synthesizers can emulate classic analogue synthesizers and modular synthesizers or even exceed their capabilities with advanced features like spectral filtering or granular processing.

Many producers appreciate the convenience of working entirely inside the computer, where patches can be saved instantly, automation is simple, and the cost is often lower than building a physical setup.

MIDI and controlling synthesizers

The introduction of musical instrument digital interface (MIDI) in the early 1980s was a game-changer for electronic music. MIDI enables communication between all types of electronic musical devices, from keyboards and drum machines to modern digital audio workstations.

This protocol transmits data about which musical note is played, how hard it’s struck, and other performance details like pitch bend and mod wheel movements.

MIDI also extends beyond note data, allowing you to control various synth parameters such as filter cutoff, LFO rate, or envelope times. With MIDI, you can sequence and automate entire performances in a digital audio workstation, making it easier to achieve complex, layered compositions.

This seamless integration underpins much of modern music production, bridging the gap between acoustic instruments and electronic instruments.

Mixing, mastering, and further processing

Once you’ve programmed your synth sounds, the next step is to integrate them into your mix. Mixing involves balancing levels, panning instruments, applying EQ, and adding effects like reverb or delay.

Mastering, however, is the final polish on a track, where the overall sonic footprint is refined for release.

Modern producers often incorporate drum machines alongside synthesizers to build cohesive electronic tracks. Drum machines use similar principles of audio signal manipulation, though they often focus on percussive samples or synthetic drum hits.

By combining well-crafted synth patches with punchy drums and skilful mixing, you can create engaging music that stands out in contemporary production.

Practical tips for using synthesizers

Efficient sound design requires a mix of structured techniques and creative exploration. Here are some useful tips for getting the most out of your synths:

Balance experimentation with methodical sound design – Explore waveforms like sine and square waves before adding filters, envelopes, or low-frequency oscillators for modulation.

Layer oscillators and synthesis methods – Combine subtractive and FM synthesis to create depth and richness in your sound.

Save preset templates in a digital audio workstation – Streamline future sessions by storing frequently used settings.

Use automation for dynamic movement – Adjust parameters like filter cutoff or amplitude to add evolving character to tracks.

Document modular synth patches – Keep track of patch cables and settings to easily recreate favorite tones.

Conclusion

Synthesizers remain at the forefront of music production, offering a limitless range of sounds and functions that surpass many modest musical instruments. By understanding concepts like oscillators, filters, and envelopes, you can truly appreciate how synthesizers work to generate everything from gentle pads to aggressive leads.

The evolution from early synthesizers to modern digital synths ensures there’s an instrument for every budget and style, whether you’re drawn to the warmth of analogue synths or the precision of digital synthesizers.

In a world where musicians constantly seek unique sound design, synthesizers offer an endless playground. The combination of additive synthesis, subtractive synthesis, and FM synthesis extends creative possibilities far beyond the capabilities of most acoustic or electronic musical instruments.

By taking advantage of MIDI, software instruments, and advanced processing options, producers can craft truly inventive music that resonates with audiences across genres.

Record, mix, and master your synths at TYX

At TYX Studios, we’re no stranger to synthesizers. Along with a load of industry-grade music tools, our studios have a diverse array on offer, from old to new.

We specialise in guiding electronic musicians through every step of production. So, whether you’re new to synthesizers or an old hand, we can help you capture and create the sounds alligned with your vision.Then, we’ll transform your mixes into exceptional final masters ready for any platform.

As an end-to-end studio complex in London,  we offer top-tier production spaces, professional guidance, mastering services, career support, and more.

Get in touch now and let us elevate your creations to professional, release-ready tracks.