The last blog looked at common Synthesizer features and can be found here.
This blog is going to focus on three common types of synthesis that you are likely to come across in the world of synthesizers.
There are different types of synthesizers and while they tend to use common oscillator types described in the previous blog, the way that these synths are designed to create and shape their sound is called Synthesis. It's often the main factor in differentiating them, giving them their unique audio characteristics. Below is some further information on these three common types of synthesis:
1. Subtractive synthesis
Subtractive synthesis is very common among hardware and software synthesizers. Some examples are: Roland's Juno 106 hardware synth, Lennar Digital's Sylenth VST and Logic pro's ES1 native synth.
An easy way to understand Subtractive synthesis is to describe the signal flow of a basic synthesizer; whereby the oscillator (sound source) is routed/sent through a filter which affects the frequency range of the sound, then passing through an amplifier for gain staging and typically passing through an ADSR to control how the sound works overtime.
It's this process of subtracting and shaping frequencies through a filter and ADSR, so that its harmonic content can be chipped away, that gives subtractive synthesis its unique characteristic and sound. Another useful definition when thinking about subtractive synthesis is the following:
“Subtractive synthesis is a method of sound synthesis in which partials of an audio signal (often one rich in harmonics) are attenuated by a filter to alter the timbre of the sound. While subtractive synthesis can be applied to any source audio signal, the sound most commonly associated with the technique is that of analog synthesizers of the 1960s and 1970s, in which the harmonics of simple waveforms such as sawtooth, pulse or square waves are attenuated with a voltage-controlled resonant low-pass filter. Many digital, virtual analog and software synthesizers use subtractive synthesis, sometimes in conjunction with other methods of sound synthesis” (Wikipedia definition)
2. Frequency modulation (FM) synthesis
Frequency modulation synthesis takes a different approach when it comes to creating and shaping a sound. It was first introduced to the musical world in the 80’s through the creation of a hardware synth called the “Yamaha DX7” and has since spawned virtual instrument versions such as Native Instruments FM8 and Ableton's Operator synth.
The basic idea behind FM synthesis is that you have one oscillator being used to effect another oscillator to produce its sound. These two oscillators are called a modulator and carrier respectively.
The pitch/frequency of the carrier oscillator is being altered by the modulator oscillator signal being fed into it. As a result of this synthesis process more complex waves forms are created that are often described as gritty, harsh, digital and bell like.
3. Wavetable synthesis
Wavetable is another common form of synthesis that you are likely to come across. Some iconic wavetables synths are: Native Instruments Massive and Xfer’s Serum both of which have been used in numerous contemporary pop and underground music tracks.
Wavetable differs from the other two types of synthesis mentioned, it's probably closer to a sampler than a synthesizer in the sense that it digitally stores one loop of a waveform (such as a saw wave, sine wave, square wave etc) and collates it into a sequence of tables of samples (Wavetables) which can then be played back.
This digital representation of a waveform or sample can be accessed individually or in a combination to recreate almost any sound you would usually find on any other synthesizer. The benefits of this type of synthesis is that it uses less processing power and memory because the waves have already been pre calculated to serve certain purposes, for example; a square wave that has been pre-filtered at different intensities to be instantly used rather than applying a filter to actively shape the sound.
Xfer Serum Wavetable synthesizer
Synths that use different types of synthesis will often share the same features (oscillator, filter, ADSR) but at a fundamental level they are different and it’s important to understand their differences if you are looking to create a ‘certain’ sound associated with one type.
The types of synthesis described in this blog are just some of the ways that synths generate and create their unique sounds. I hope these two blog have shed some light and given you a solid understanding of the three most common types of synthesis and features found in most synthesizers.