When you go to school to learn about sound design, you learn a lot about MIDI Programs, Electronic Music, and Synthesizers. Understanding each of these technologies is important to sound design and sound synthesis training. In the 1960’s, subtractive synthesis became a lot more popular. By the 70’s, this form of synthesis was available to the masses. Only a handful of components are necessary for the subtractive synth to give you a wide range of sounds. This makes it great for early synth designers who needed accessible and affordable synthesizers.
In the early 1900’s, additive synthesis was first seen as the tonewheel based instruments were created. The concept of these was first seen, though, in 1822 by Joseph Fourier and his research on harmonic analysis.
You can achieve both forms of synthesis through using some basic elements such as amplifiers, filters, and oscillators. The primary difference between the two forms is their approach, not their parts. Below will tell how the approaches of the two differ.
A subtractive synthesizer provides you with oscillator wave shapes like square, sawtooth, triangle, and sine. Since a sine wave only generates one frequency, it is known as a pure tone. Other wave shapes give you even and odd harmonics that are above the fundamental frequency that they are tuned to. The concept is to generate a higher number of harmonics than you want with subtractive synthesis, then subtract certain frequencies with a filter. Therefore, all subtractive synthesizers must use a minimum of one filter.
There are oscillators with additive synthesis too, but they only have one wave shape with those oscillators, the sine wave. If you go this route, you only want to build the sound with one harmonic at a time. Each of the sine wave oscillators is at a specific frequency that corresponds with a single harmonic. It is a lot like creating with Legos, in that you build with one block at a time. The higher number of clocks you use, the better your sculpture can be realistic. Additive synths typically have more oscillators and do not need a filter like the subtractive synths do.