A lot of people out there are really interested in synths but just don’t know where to begin, in these articles I will give you an extremely basic, beginner’s guide to synthesis. Here we’ll briefly look at additive and subtractive synthesis.
What is additive and subtractive synthesis?
Additive synthesis is a sound technique that uses sine waves to produce a certain timbre (the sounds quality). Whereas Subtractive is a technique that uses a filter to effect partials of the sound wave which changes the timbre produced.
Additive Synthesis can be dated back to the 1900s looking at some instruments using a tonewheel like the Hammond Organ. The basis of additive synthesis has been built on a theory known as Fourier’s Theorem. This is from Joseph Fourier’s research on harmonic analysis which dates back to 1822.
Additive synthesizers have oscillators but usually only use the sine wave. With this you only build your sound one harmonic at a time (a harmonic is a note produced that usually comes in a series). The other oscillators are tuned so that the frequency corresponds with certain harmonics. This means the more oscillators you use the more specific and detailed your final sound is.
Subtractive synthesis came to the forefront of the synth scene around the 1960s, it was also available to the general public. Standard subtractive synths only require a few components to work but this didn’t hold back these machines at all. They could produce various sounds and became one of the first types of early synths that were affordable e.g. the legendary Minimoog.
These synths often come with multiple waveshapes like sine, saw, triangle and square to name a few. Sine waves can only generate one frequency whereas other waveshapes can generate multiple harmonics. The basis behind subtractive synthesis is to generate as much harmonics as you wish and then use a filter to sculpt the sound you want. This means all subtractive synths must have at minimum one filter.