As technology has evolved, the methods used by synthesizers to generate their sounds have changed. Nowadays, there is a myriad of different ways that synths operate, each with their own characteristic sound.
The differences between these can be a bit confusing to the beginner, so to help, here’s a guide to some of the most common types of synthesis.
Subtractive synthesis is the type of synthesis most closely associated with the analogue synthesizers of the ‘60s and ‘70s. Many modern synthesizers and plug-ins emulate the synthesis method, however (those termed ‘virtual analogue’ are usually based on additive synthesis- Reason’s Subtractor synth is a great example).
Essentially, it involves taking a sound source (oscillator) that is rich in harmonics, and taking bits of it away to create the sound.
So, you might take a wave like a sawtooth, and use a filter to remove certain harmonics. Then, envelopes might be used to shape the attack, decay, sustain and release of the sound.
In many ways, it’s a similar process to the way the voice works. The vocal chords are the ‘oscillator’, and the mouth acts as a filter, reducing the harmonics heard according to how widely it is opened.
This sype of synthesis sounds very vintage, and very obviously synthetic, which is a big part of its appeal (think Kraftwerk, the BBC Radiophonic workshop, and just about every dance music track ever for an idea about its sound).
Subtractive synthesis is a great way to learn about how synthesis works. Roland’s GAIA synth, and Reason’s Subtractor are great subtractive synths to learn on.
PCM Based Synthesis
PCM stands for Pulse Code Modulation’, which basically means that it uses samples as it’s primary sound source. For the uninitiated, samples are digital recordings, so a piano sound will start out as a digital recording of a real piano, a guitar will be a recording of a guitar, etc.
The advantage of PCM over other types of synthesis are that recreations is that acoustic instruments can be made to sound very authentic, which is nearly impossible with other types.
Nowadays, sounds are constructed by using many different samples (every key of a piano at multiple velocities, for example), with clever switching used to play the correct sound at the correct velocity. In addition, ‘scripting’ is sometimes used to give sounds even more authentic articulation.
On some string sounds, this might include alternating between samples of different bowing directions if fast passages are being played. Most PCM synths also employ elements of subtractive synthesis, too (such as filters).
PCM synths will generally have a very wide range of sounds, too, as it is simply a matter of including more samples of different instruments. Check out Native Instruments Komplete for excellent examples of how this can sound.
FM (Frequency Modulation) synthesis was one of the first digital synthesis methods. It first appeared in the legendary Yamaha DX7.
The way that FM synthesis works is that a simple waveform called a carrier (sine, saw, square, triangle) is modulated by another wave, called a modulator. The result is a far more complex waveform.
These waves are known collectively as operators, and an FM synth can have many operators to shape its sound to increasingly complex waves.
The main advantages of FM were that waves of unprecedented complexity could be produced. In particular, sounds with bell-like qualities could be produced with a level of authenticity never heard before.
Today, the most popular of all FM synths is Native’s FM8, available in the Komplete packages (which will also provide great examples of all the types of synthesis mentioned here). If you want to add a bit of an ‘80s vibe to track, this is a really authentic way to do it.
The best way to hear what the different types of synthesis have to offer is to experiment, of course. For more information about any of the products above, call our stores or customer service team (01925 582420), see our online store here for hardware synths, and here for software instruments.
Joe is a contributor for the Dawsons Music blog. Specialising in product reviews and crafting content to help and inspire musicians of all musical backgrounds.