The synthesizer is now an essential part of today’s modern studio, and any aspiring music producer should be able to answer the question, how do synthesizers work? Understanding how they work will open up a whole world of sound creation and manipulation that can transform your recordings and productions. It’s definitely one of my favorite instruments found in the studio.
A synth (sometimes seen as synthesiser) is an electronic instrument that can create a wide range of different sounds and textures. They can be used to imitate real instruments, or to create completely new sounds that have never been heard before.
Synths come in both hardware and software versions. You can now find software emulation plugins of the most famous and well-known hardware synths from years gone by, helping modern-day producers to achieve those classic synth sounds at the fraction of the cost of the original models.
The actual notes produced by most synths are controlled by keyboards. The tonal qualities of the sounds are controlled by all of the knobs, buttons and sliders found on the synth’s control panel. Most synth parameters can now be controlled through MIDI as well, helping producers create more dynamic sounds that can change shape and texture over time.
How Do Synthesizers Work – Synthesizer Building Blocks
You’ll find that the controls on a synth, whether hardware or software, are mainly based around the same principles of audio synthesis.
- Oscillators (VCO): these generate the raw sound that is later shaped by other controls. Most synths have 1, 2, or 3 oscillators, with each one able to produce different sounds depending on the shape of the wave used – the common wave types are sine, square, triangle, and sawtooth. The sounds of each oscillator can then be combined.
- Filters (VCF): these can come in a few varieties – hi-pass, lo-pass, bandpass, or notch. The filter removes frequencies from the sound – the frequency where the filter effect takes place is called the cutoff frequency. The ‘Q‘ value can emphasise this selected frequency by making it resonate, helping to produce a unique sound.
- Amplifier (VCA): boosts the signal to alter the sound’s volume.
- Envelope: ‘shapes‘ the sound using parameters called attack, decay, sustain, and release – this is why they are known as ADSR envelopes.
- LFO: Low Frequency Oscillator. This oscillator doesn’t produce sound like the VCO, but is used to directly affect the sound generated by the synth. The LFO can be assigned to affect different parts of the sound – for example, it can create rhythmic effects such as vibrato by oscillating the amplifier, or create filter sweeps by oscillating the filter cutoff frequency.
Here’s how you create a sound using a synthesizer:
- The oscillator produces the sound (you can use one oscillator or combine several together)
- The filter removes certain frequencies from the sound
- The ADSR envelope shapes the sound
- The LFO can be applied to any of the above three stages, helping to produce wildly different sounds
You may be wondering how each waveform produces it’s characteristic sound. Each waveform has it’s own unique mixture of a fundamental frequency along with harmonic frequencies (or overtones), and each harmonic frequency is a simple multiple of the fundamental frequency.
For example, if the fundamental frequency is 220 Hz (the note ‘A’), then the first harmonic would be at 440 Hz, the third at 660 Hz, and so on. The balance of the fundamental frequency and the different harmonic frequencies is what gives each different waveform it’s unique sound.
- Sine Wave: the purest sound waveform out of the four, with no harmonics involved at all. Sine waves form the basis of all other waveforms
- Square Wave: these waveforms contain harmonics, contributing to the square shape
- Sawtooth Wave: the sawtooth wave has the highest harmonic content amongst the four types of wave
- Triangle Wave: similar to the square wave, but the harmonics in the triangle wave are less powerful
One of the modular synths that was first commercially available to musicians and producers was the famous Moog instrument in 1965. ‘Modules‘ could be bought separately and then connected together – this allowed modular synthesis systems to be built up over time, as the modules were very expensive to buy.
Some of the modules available were:
- VCO – Voltage-Controlled Oscillator
- LFO – Low-Frequency Oscillator
- ADSR envelope – Attack/Sustain/Decay/Release
- VCF – Voltage-Controlled Filter
- VCA – Voltage-Controlled Amplifier
- Ring Modulator – when you hear that well-known robotic or metallic sound, then that’s a ring modulator at work
- Mixer – this combines all the various signals from the other modules in the synthesizer
- Sequencer – these modules can create patterns of notes and sounds. Below is a video of some of the sequencer options found on the Arturia MicroBrute synth ->
Modular synths have made a massive comeback over recent years and these modules are available from lots of different synth makers.
I definitely think it’s worth learning about the different parts of the synthesizer so you can answer that all-important question – how do synthesizers work? It then becomes much easier to get stuck into creating new and exciting synth sounds for your music productions. Coming up with these new sounds can be fun and can inspire whole new directions for your music.
The synthesizer is one of the most important and influential instruments used in music creation, and if you can learn how to use them then you’ll be one step closer to creating amazing productions.