Additive  & Subtractive synthesis

Additive synthesis

Additive synthesis is the process of adding together multiple Sine waves together to create a different timbre. Technically any waveform could be used to do this such as a square wave or a saw wave, however, Sine waves are the purest waves. This is because sine waves are perfectly curved meaning you can never multiply straight lines to get a sine wave. Additive was created in 1935 by an American inventor named  Thaddeus Cahill. 



Subtractive synthesis

Subtractive synthesis is the process of taking away frequencies to create a thinner timbre. Unlike additive synthesis subtractive synthesis is used with multiple different waves to create its sound. This could include saw waves, square waves or triangle waves. Subtractive synthesizers often start with an oscillator this is a device which creates the original sound. This sound is then fed into a filter where frequencies can be subtracted and then this signal is sent to an amplifier to make it audible. 




The difference

Subtractive and additive synthesis are both very useful tools to producers. Despite the fact that they are both forms of synthesis they work slightly differently. Both forms of synthesis can be achieved using basic synthesis elements such as oscillators, filters, and amplifiers. The fundamental difference between these two forms of synthesis is not in their parts but more in their approach.



Here is a diagram showing the noise chain of a subtractive synth and an adaptive synth.





The graph shows that there is a clear difference between the way these two machines work. The first difference is that with subtractive synthesis only one oscillator is used this is because it is working restrict the amount of frequencies heard however additive synthesis is trying to sine waves together t create a bigger sound. The second difference is where the sound goes into. With subtractive synthesis, the sound goes into a filter this filter takes out unwanted harmonics and helps to isolate different waves. Additive synthesisers do the opposite, additive synthesise works to add sounds together so the sounds go into a mixer which combines all the sounds together.



These two processes are also built on 2 different theory. Subtractive synthesis is based on the theory that every sound in the world can be taken down to a pure sine wave. This is how subtractive synthesis works. Additive synthesis is the inverse of this law. Additive synthesis follows a law called the Fourier Transform theory which is based on the premise that if you are able to convert any sound to sine waves then you are also able to create any sound in the world using sine waves.