What are the different types of synthesis?

The electronic music landscape has been forever transformed since the inception of the Minimoog in the 1960s, igniting the synthesizer revolution. Over the years, a plethora of hardware and software-based synthesizers have flooded the market, each offering unique methods to sculpt sound. This article aims to shed light on the diverse techniques employed by these instruments to synthesize a wide range of captivating sounds.

Understanding the Synthesis Landscape

As the musical landscape evolved, so did the methods of sound creation. Synthesis became the cornerstone of innovation, enabling musicians to sculpt tones and textures that transcend traditional acoustic realms. Understanding the array of synthesis techniques is essential for producers and enthusiasts seeking to expand their sonic palette.

Subtractive Synthesis: The Time-Tested Pioneer

A logical starting point in the world of synthesis is subtractive synthesis. Pioneers of early synthesizers gravitated towards this method, drawing inspiration from the natural way humans vocalize sounds. The concept is simple: a sound source and a modifier work in tandem. Just as vocal cords produce sound and the mouth shapes it, oscillators serve as sources, while filters function as modifiers in the realm of synthesis.

Oscillators generate waveforms like sawtooth, pulse, triangle, or square, which are then shaped through filters, envelopes, and other parameters to chisel out desired frequencies. Subtractive synthesis mimics the way our vocal apparatus shapes sounds, making it an intuitive starting point for sonic exploration.

Additive Synthesis: Harmonic Stacking for Complexity

Additive synthesis is closely linked to subtractive synthesis, yet takes a distinct approach. Rather than subtracting frequencies, additive synthesis involves stacking multiple sine waves to create complex harmonics. This method allows precise control over each sine wave’s frequency and amplitude, potentially recreating any natural sound. However, the practicality of achieving perfect replication is limited by the sheer number of oscillators required for intricate sounds.

Resynthesis: Merging Analysis and Synthesis

Resynthesis marries additive synthesis with a twist. While both methods employ stacked sine waves, resynthesis involves analyzing input sounds’ frequencies to recreate their harmonic structure. In contrast, traditional additive synthesis lacks an input sound to recreate. Imagine wanting to emulate an 808-inspired bass patch: additive synthesis necessitates manually stacking waves, while resynthesis involves uploading a sample, allowing the software to handle synthesis.

Wavetable Synthesis: Dynamic Waveform Morphing

Wavetable synthesis is a method in which a variable number of wave cycles are spread across a wavetable. When a key or chord is played the synthesizer uses different methods such as looping or pitch-shifting to make its way from one wave cycle to another, thus producing interesting harmonics.

Let’s break it down: Picture a sawtooth wave. What you should see is a repeating waveform with a sharp upward rise followed by a vertical drop from its peak. This rise and fall “loop” is known as a wave cycle. During the digital synth revolution of the late-1970’s computer memory and processing power were expensive. The inventor of wavetable synthesis realized that storing a single cycle of a waveform was more advantageous than generating and processing them on-the-fly.

Wavetable synthesizers are great for producing evolving pads, dynamic strings, and punchy bass sounds. Wavetable synthesis is often compared to Linear Arithmetic (LA) and Granular synthesis. These three methods do, indeed, share some common traits; yet, when you take a peek under the hood you’ll see that the similarities are only surface deep.

For example, LA synthesis was designed to use samples in a manner that emulates traditional instruments. Granular synthesis, on the other hand, is more akin to wavetable synthesis because it works by splitting a sound into many parts. These sound particles or “grains” are many times smaller than those used in wavetable synthesis. Even more, when a key is pressed the grains are rearranged in a manner that requires a ton of processing power, directly contradicting the design philosophy of wavetable synthesis.

Frequency Modulation Synthesis: Digital Brilliance

Frequency modulation synthesis is in a class of its own. This technique was popularized by Yamaha and has become the most commercially successful synthesis method of all time (according to DX7 sales). FM synthesis works by using a carrier and a modulator. Harmonics are created when the frequencies of the carrier are modulated by the modulator.

FM-based synthesizers don’t sound like others. These synthesizers tend to have a more “electronic” or “digital” sound than most. And although pads, leads, and vocal sounds are possible, FM synthesis is really great when it comes to creating bright epiano, thick bass sounds, synthetic brass, and bells.

What is pulse code modulation synthesis?

Also known as sample synthesis, pulse code modulation (PCM) synthesis is a method which involves using samples instead of oscillators. If you didn’t know, a sample is a digital recording. It could be a piano, trumpet, cello, hand clap, or any other recording.
In recent years technology has progressed to the point where PCM-based instruments provide near-perfect replication of acoustic sounds. The use of innovative algorithms allows for seamless switching from one sample to another providing a truly authentic sound. In other words, nothing beats PCM-based synthesizers if you’re looking to mimic acoustic instruments.

What is phase distortion synthesis?

Phase distortion synthesis is different from other methods in the way the oscillator generates waves. It’s actually very simple; in short, a sine wave is bent into shape by the user to form new (or familiar) waveforms. Unlike traditional subtractive synths where you have a predefined set of waves to choose from, phase distortion synthesizers provide an unlimited number of waveforms from which your sound can be shaped.
Aside from the unbounded oscillator, phase distortion synths utilize many of the common parameters found on subtractive synthesizers.

In the End, a Sonic Odyssey

Navigating the world of synthesis is akin to embarking on a sonic odyssey, where each method paints a unique brushstroke in the canvas of sound. From subtractive to additive, resynthesis to wavetable, frequency modulation to pulse code modulation, and phase distortion to many others not covered here, each technique unveils a distinct path to sonic exploration. Producers and enthusiasts alike can harness these methods to craft sounds that transcend the boundaries of traditional instruments, embracing the boundless realm of synthesized creativity.