Guide to Synthesizers: What They Are & How to Use Them

Synthesis is a powerful tool in music production, enabling you to create a wide array of sounds, from the deepest basses to ethereal pads. This technique has fundamentally transformed the landscape of music, introducing a broad spectrum of new sounds and sparking the creation of new genres. Engaging with synthesis not only involves manipulating controls but also deepens your understanding of sound, enhancing your control over your musical expressions.

 

In this guide, we will explore the essentials of synthesizers using SynthCell, a comprehensive synth plugin available in Pro Tools. We will start with the basics of oscillators and waveforms, then dive into the functions of filters, and further explore sound modulation using LFOs and envelopes. This knowledge provides a solid foundation for mastering any synthesizer. Let's begin!

 

Jump to any section:

• What is a synthesizer
• How a synthesizer works
• How to use a synthesizer
• Performance features in a synthesizer
• Get Started with Synthesis

What is a synthesizer?

A synthesizer is an electronic musical instrument that generates and manipulates electrical signals to produce sound. Unlike traditional instruments where sound is created through physical vibrations—like strings in a guitar—synthesizers create sound through electronic vibrations. These vibrations are generated electrically, using various oscillators to produce distinct waveforms. Initially developed as analog instruments, synthesizers evolved significantly with the rise of digital technology in the 1980s. Digital synthesizers and software-based synthesizers within Digital Audio Workstations (DAWs) now offer unprecedented flexibility and sound design capabilities, allowing musicians to create, modify, and automate sounds in ways that were previously unimaginable.

How a synthesizer works

The core of a synthesizer's functionality lies in its ability to create and manipulate sound through electronic signals. The process begins with an oscillator, which generates raw audio signals in basic waveforms such as sine, square, or sawtooth. These signals are then shaped through various components.

1. Filters: These adjust the timbre of the sound by removing specific frequencies, thereby altering its brightness and color.

2. Envelopes: These shape the amplitude of the sound over time, defining how it starts, sustains, and fades out.

3. Modulation: Additional expression is added by modulating parameters like pitch, volume, and timbre using Low-Frequency Oscillators (LFOs), further envelopes, and modulation wheels.

 

This structured approach not only creates the distinctive sounds of a synthesizer but also offers extensive creative control over the production of electronic music.

How to use a synthesizer

Understanding the basic parts of a synthesizer and how they interact is essential for creating a diverse range of sounds. Each component plays a distinct role in sculpting the final sound output, and learning to use them together is the essence of sound design. We’ll now dive into the synthesis workflow and explore some of the most common parameters you have to shape sound. Feel free to follow along with the accompanying video to see these concepts in action with SynthCell in Pro Tools.

1. Select your oscillator waveforms

Oscillators are where synthesis begins, acting as the primary sound generators in a synthesizer. They create the raw electronic sounds that you’ll shape with the synthesizer’s various controls. Synthesizers typically have two or three oscillators, each with their own waveform and set of controls:

 

Waveform Selection

 

Choosing a waveform is the first step in shaping the sound from an oscillator. Each waveform type—sine, square, triangle, and sawtooth—has a distinct set of harmonics, defining its unique sound profile:

• Sine Wave: The sine wave is the simplest waveform, producing a pure tone without any harmonics. Its sound is smooth and mellow, often compared to a whistle or a soft hum. It's commonly used for sub-bass sounds, simple melodic lines, and emulating instruments like flutes or soft organ sounds.
• Square Wave: Square waves have a distinct, hollow timbre due to their rich odd harmonic content. They can sound punchy and present, which makes them excellent for creating classic bass sounds, retro chiptunes, and synthetic woodwind-like tones. A square wave's pulse width can often be modified, which alters the timbre, offering even more sonic flexibility.
• Triangle Wave: A triangle wave sits between a sine and square wave in terms of harmonic content. It has a slightly more buzzy quality than a sine wave but is softer and less brash than a square wave. This makes triangle waves useful for softer basses, flutes, and when you want a sound with a bit more edge than a sine wave but not as aggressive as a square or sawtooth wave.
• Sawtooth Wave: Known for its bright and edgy sound, the sawtooth wave contains both even and odd harmonics, making it rich and full. It's a staple for brass sounds, aggressive lead synths, and buzzy basses. It's one of the most harmonically rich and bold waveforms available on a synthesizer, making it ideal for cutting through a mix.

 

The choice of waveform is often the first step in sound design, as it sets the foundational tone which will be shaped and refined by the synthesizer's other components. By understanding the intrinsic qualities of each waveform, you can better select the right starting point for the sound you aim to create.

 

In addition to selecting a waveform, the oscillator section of a synthesizer offers several other parameters to further shape the initial sound:

 

• Octave Control: This parameter allows you to shift the pitch of the oscillator's output up or down by octaves. This is used to place the sound in the correct register, whether you're aiming for a deep bass or a high-pitched lead.
• Multi-Voice Oscillators: Some advanced synthesizers include multi-voice or unison features within a single oscillator. In SynthCell, oscillator 1 has a multi-voice option which allows you to stack multiple instances of the same waveform to play simultaneously, thickening the sound considerably. This is especially useful for creating rich, supersaw-type leads or powerful basses that stand out in a mix.
• Detune Control: When using multiple voices, detuning them slightly against one another can create a sense of width and depth in the sound. Detune can introduce a slight pitch variation between voices, which results in a chorusing effect, adding complexity and richness to the sound. This is often used to make a sound more lively and less static.
• Pulse Width Modulation (PWM): Specifically for square waves, this controls the width and symmetry of the square wave. By shifting the symmetry of the square wave, you can change it’s timbre allowing for a variety of unique textures.

 

2. Fine-tune filter for desired timbre

After selecting a waveform and shaping the initial sound with the oscillator, the next major component of a synthesizer is the filter. Filters allow you to control which frequencies are allowed to pass, giving you the ability to control the sound’s brightness and texture.

There are several types of filters, each with its characteristics:

 

• Low-Pass Filter (LPF): This is one of the most used filter types in synthesis. It allows frequencies below a certain cutoff point to pass through while attenuating frequencies above this point. Low-pass filters are great for creating warmer, more subdued sounds or for removing harsh high frequencies.
• High-Pass Filter (HPF): Opposite to the LPF, a high-pass filter cuts off frequencies below a certain point and lets higher frequencies through. This type of filter is useful for making a sound feel thinner or for removing rumble and low-end noise from a signal.
• Band-Pass Filter (BPF): A band-pass filter allows frequencies within a certain range to pass through, cutting off frequencies below and above this range. It's useful for creating telephone or radio-like effects, where you want to focus on a specific band of frequencies.

 

Each filter type can often be adjusted in terms of:

 

• Cutoff Frequency: This control sets the point where the filter begins to affect the sound. Moving the cutoff frequency allows you to determine the position of the filter in the frequency spectrum which shapes the brightness or darkness of the sound.
• Resonance (or Emphasis): Increasing the resonance emphasizes the frequencies around the cutoff point, which can add a sharp peak to the sound, sometimes even leading to self-oscillation, where the filter itself begins to generate a tone.
• Key Tracking: Some synthesizers allow the filter cutoff frequency to track the keyboard, meaning higher notes can be set to have a higher cutoff frequency automatically, maintaining a consistent timbre across the keyboard.

 

3. Shape articulation with amp envelope

After shaping the frequency content with filters, we approach the final major component of a synthesizer: the amplitude envelope. This parameter gives you control over how the volume of the synthesizer changes every time a note is triggered, effectively shaping the sound's dynamics and articulation. The amplitude envelope is where you determine whether a sound starts and ends quickly like a sharp and transient sound, or whether it starts and ends slow like an ambient, sustained pad. Think of it like an automated volume knob.

The envelope consists of four primary components—attack, decay, sustain and release, collectively known as ADSR:

• Attack: Defines the time it takes for the sound to reach its maximum level after the key is pressed. A quick attack means the sound starts abruptly, suitable for punchy, percussive sounds. A slower attack results in a gradual fade-in, perfect for pads and atmospheric sounds.
• Decay: The time it takes for the sound to drop from the initial peak reached at the end of the attack phase to the sustain level. Short decay times can add a sharp, transient character, while longer decay times allow the sound to gently decrease to the sustain level.
• Sustain: Unlike the other parameters, sustain is a level, not a time. It represents the volume at which the sound holds as long as the note is pressed. A high sustain level keeps the note loud, while a low level will result in the sound dying down after the decay phase.
• Release: Dictates how long the sound takes to die away after the key is released. A quick release will cut the sound off abruptly, which is useful for staccato effects. A longer release lets the sound tail off slowly, allowing for a natural decay, much like the ringing out of a piano note.

By adjusting these ADSR parameters, you can significantly alter the sound's character, turning a simple waveform into a complex and dynamic element in your music.

 

4. Add movement with modulation

After shaping the foundational sound of your synth patch with the oscillators, filters, and the amp envelope, we can shift our focus to modulation, the technique that adds movement andlife to your sound. Normally, adding movement to a sound involves manually adjusting knobs and parameters. However, modulation functionality in synthesizers allows for this 'knob turning' to be automated, freeing you to create dynamic, evolving textures that can be impossible to do by hand. The main sources of modulation you can use in a synthesizer to automate parameter changes are LFOs and mod envelopes. Let’s take a look at what they are and the differences between them:

LFOs (Low-Frequency Oscillators)

LFOs, or Low-Frequency Oscillators, are a cornerstone of modulation in synthesizers, offering a way to automatically control various parameters over time. Unlike the audio-rate oscillators that create the sounds we hear, LFOs operate at much lower frequencies and are not heard directly. Instead, they modulate parameters like pitch, volume, and filter cutoff to add movement and interest to the sound.

 

An LFO has different controls that allow you to shape how you modulate another control on the synthesizer. Let’s go over common parameters:

• Waveform: An LFO can typically be set to a variety of waveforms, with each shape influencing how the modulation occurs.
• Rate: This determines the speed of the modulation—the speed of how quickly a knob is turned. If an LFO is assigned to the oscillator pitch, for example, a slow rate can sway the pitch gently for a soothing vibrato.
• Retrig: "Retrig" or "Retrigger" determines how the LFO behaves when a new note is played. With retrig on, the LFO waveform starts from the beginning each time a key is pressed. This is especially useful for rhythmic precision in playing patterns. Without retrig, the LFO continues its cycle independent of new notes, allowing for a more free-flowing and unpredictable modulation, which can add a unique, evolving character to sustained sounds.

 

Modulation Envelopes

While LFOs provide continuous, cyclic modulation, modulation envelopes offer a one-time, shapeable modulation curve to a sound parameter, following the classic ADSR (Attack, Decay, Sustain, Release) structure. This allows for precise control over how a parameter evolves from the moment a note is triggered until it's released. A common application is a filter envelope, which changes the position of the cutoff frequency of a filter across the duration of a note, adding expressiveness to a sound by making it grow brighter or darker. Unlike LFOs, the modulation effect of an envelope is non-repeating, unfolding according to the ADSR settings. This one-off modulation curve is especially useful for sculpting the character of a sound, from the initial attack to its sustain and eventual release.

 

Modulation matrix

Once you choose your mod source, you have to assign it to the parameter you want to modulate. In synthesizers, a mod matrix, short for modulation matrix, is where you route various modulation sources to different destinations within the synthesizer. Instead of turning a knob with your hands, you can assign an envelope, LFO, aftertouch, etc., to perform these actions for you. This is often done through a grid or a list where you can select a source and a destination and then apply an amount of modulation. This amount might be a positive or negative value, determining how much the destination parameter changes in response to the source.

Here's a breakdown of how it works:

• Source: These are the modulation sources that generate control signals used to modify various parameters of the synth's sound. Common sources include LFOs (Low Frequency Oscillators), envelopes, sequencers, aftertouch, and external inputs (like MIDI CC messages).
• Destination: You can assign a source to modulate almost any parameter on a synthesizer. The destination on a mod matrix shows the parameters within the synthesizer that can be modified by the modulation sources. Typical destinations include oscillator pitch, filter cutoff frequency, amplifier level, effects parameters, and many others.
• Depth/amount: For each modulation routing, you can also specify the depth (or amount) of modulation, which determines how much the destination parameter is affected.
  

  The mod matrix is a powerful tool for sound design, enabling complex and dynamic changes to the sound. It allows for a high degree of customization and can make synthesizers capable of a wide range of sounds—from subtle variations to dramatic transformations.

Performance features in a synthesizer

Other features you'll encounter with a synthesizer fall within the category of performance features, designed to extend the expressive capabilities of your instrument beyond basic sound generation. These include tools like the pitch and mod wheels, which allow for real-time expression, and operational modes like the arpeggiator and monophonic vs. polyphonic settings that dictate how your synthesizer reacts to each note played. Through these features, you gain the ability to dynamically shape your performance, adding depth and emotion to the synthesized soundscape.

 

Glide/Portamento

Glide, also known as portamento, is a feature found on many synthesizers that creates a smooth pitch transition from one note to another. So instead of the pitch jumping directly to the second note, it smoothly transitions or "glides" from the pitch of the first note to the pitch of the second. This creates a continuous pitch movement that can be fast or slow, depending on how you set the time and rate of the glide.

 

Glide is not for every sound, but it’s an effect that can add expressiveness and a unique character to your sound, making it particularly popular in lead lines, bass sounds, and even atmospheric pads.

 

Polyphonic vs. Monophonic

In synthesizers, the terms "polyphonic" and “monophonic” refer to the instrument's ability to play multiple notes simultaneously or just a single note at a time. Understanding the distinction between these two modes is essential for both sound design and performance, as they significantly influence the synthesizer's behavior and the types of sounds it can produce.

 

Polyphony

Polyphony in synthesizers allows for multiple notes to be played at the same time, enabling the creation of chords, layered textures, and complex melodic sequences. The degree of polyphony refers to the maximum number of notes that can be sounded simultaneously. For example, a synth with 8-voice polyphony can play up to eight notes at once.

 

• Chordal Playing: Polyphonic synths excel at playing chords, making them ideal for accompaniment and harmonic compositions.
• Layered Sounds: They allow for the stacking of notes to create rich, textured sounds.
• Versatility: Polyphonic synths can switch between monophonic lines and polyphonic chords, offering a wide range of expressive possibilities.

 

Mono Mode

Mono mode, short for monophonic, restricts the synthesizer to playing only one note at a time. This limitation might seem like a drawback, but it actually lends itself to a focused and powerful sound, often preferred for lead lines, bass parts, and solo passages. Monophonic synthesizers typically offer additional features like portamento or glide, which smoothly transitions the pitch between notes for expressive slides and bends.

 

• Lead Lines: Mono mode is perfect for distinct, prominent melodies that cut through a mix.
• Bass Sounds: The restriction to one note ensures clear, punchy bass lines without the muddiness that can come from overlapping notes.
• Glide/Portamento: This effect is more pronounced and useful in mono mode, adding expressiveness to melodies.

 

Switching Between Modes

In SynthCell, you can switch between polyphonic and monophonic modes, giving you the flexibility to adapt to different musical contexts. Some synthesizers even offer additional modes, such as unison, where all available voices are used to play a single note, thickening the sound for a more robust output.

 

The choice between polyphony and mono mode depends on the musical application and desired sound. Polyphony opens up a world of harmonic and layered possibilities, while mono mode focuses on delivering powerful and articulate single-note lines. Both modes have their place in music production and performance, making them valuable tools in the synthesizer's arsenal.

 

Arpeggiator

An arpeggiator is a feature found in many synthesizers that automatically steps through a sequence of notes based on the chords you play on the keyboard. It's a powerful tool for creating rhythmic patterns, pulsating sequences, and complex melodic lines with minimal effort. By holding down a chord, the arpeggiator cycles through the notes of that chord in a pattern. Common parameters in an arpeggiator include:

 

• Mode: Determines the order in which the notes are played. Common modes include up, down, up/down, random, and more, each creating a different feel and texture.
• Range/Octave: Specifies how many octaves the arpeggiator will cover, allowing the sequence to jump beyond the original notes played.
• Rate: Controls the speed of the arpeggiation, from slow, unfolding patterns to rapid, staccato sequences.

 

Pitch Wheel

The pitch wheel is a performance tool found on most synthesizers, designed to bend the pitch of the notes being played. This can be used for expressive effects like vibrato, bends, and portamento. Unlike preset pitch modulation effects, the pitch wheel provides real-time control, allowing for immediate pitch adjustments during performance, adding a human touch and expressiveness to the synthesized sound.

 

Mod Wheel

The modulation wheel, or mod wheel, offers real-time modulation control, typically influencing aspects like vibrato depth, filter cutoff, or LFO rate. Its primary function is to add expressiveness and variation to the sound as you play. Unlike the pitch wheel, which specifically alters pitch, the mod wheel is assignable to a wide range of parameters, providing a hands-on tool for dynamic expression and sound sculpting.

 

Together, these performance features and voicing modes open a world of expressive potential, enabling synthesists to navigate seamlessly between intricate sound design and dynamic, emotive performances. Whether crafting a studio production or performing live, mastering these elements can elevate your music, bringing depth, emotion, and complexity to your sonic explorations.

Get started with synthesis

As you continue your journey with synthesis, remember that experimentation and practice are key. Each step you take builds upon the last, expanding your creative possibilities and enhancing your musical projects. For your next steps, dive into programming specific sounds—like basses, pads, plucks, and leads. Experiment with layering different waveforms, tweaking the filter cutoff and resonance, and applying various modulation techniques to add movement and interest to your sounds. With each new sound you create, you'll gain a deeper appreciation for the art of synthesis and a greater command of your musical palette. Check out SynthCell in Pro Tools and start exploring!