How a Synthesizer Works

A Minimoog from Moog Music

The synthesizer is now an essential part of today’s modern studio, and any aspiring music producer should understand how one works – it will open up a whole world of sound creationand manipulation that can transform your recordings and productions. It’s definitely one of my favorite instruments found in the studio.

A synthesizer can produce a wide range of soundsA 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.


Synth Controls


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.

Below is a picture of a Minimoog that shows a typical layout for a hardware device – this design was released in 1970 as a smaller compact version of the famous Moog modular synth that was first released in the mid 1960s. The Minimoog was relaunched in 2002 as the Minimoog Voyager.


A Minimoog from Moog Music


It’s a classic model and design, and one of my favorite instruments to play.


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-passlo-passbandpass, 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.

ADSR Envelope The key on the keyboard is pressed – the attack is the time it takes the sound to reach it’s full volume. The decay is the time it takes this maximum volume to fall to the volume set by the sustain.


The ADSR envelope shapes how the note is heard


The sustain is the volume level of the sound during the time the key is pressed. The release is the time it takes the volume to reach zero once the key has been released.


  • 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.


Modular Synthesizer


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:

  • A modular synth, made up of different modulesVCO (Oscillator)
  • LFO
  • ADSR envelope
  • VCF (Filter)
  • VCA (Amplifier)
  • Ring Modulator
  • Mixer
  • Sequencer


Final Thoughts


I definitely think it’s worth learning about the different parts of the synthesizer, as 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.