Subtractive Synthesis – Part 2

Okay… if Subtractive synthesis is nothing but carving out unwanted sounds from a raw material sound, what exactly is the raw material sound, and how do we go about carving it?

We know that sounds are all about frequencies. Everything we hear is either a single frequency, or multiple frequencies of sounds colliding with each other to give an impression of unified sound. So it makes sense that the sound raw material is a set of frequencies that are generated. The carving process is basically the removal of unwanted frequencies so that only the frequencies that should be present in the sound we want is finally heard.

These two relate to two important parts of any synth.

The generator of frequencies is usually called the “generator” (duh!) or “oscillator” (In physics, something has to oscillate for sound to be produced. Like a tuning fork, or a plucked string).

The carving of frequencies is done by what is called a “filter”. True to it’s name, it filters frequencies – It lets the wanted frequencies through and filters out the unwanted frequencies.

With me so far?

There are different types of generators and different types of filters. The combinations of these two alone can produce a variety of sounds.

Of course, apart from generators and filters, there are other parameters to modify sound, and we’ll come to that later.

But for now, let’s see that Wikipedia definition again.

Subtractive synthesis is a method creating a sound by removing harmonics, characterised by the application of an audio filter to an audio signal.

To summarise, in subtractive synthesis, you take an audio signal, and you selectively remove harmonics ( frequencies) using filters to create a sound.

See, I told you it was simple!

Now it’s time to actually do this! In the next post, we’ll use Clearsynth to create our first sounds.


1 Response to “Subtractive Synthesis – Part 2”

  1. January 12, 2010 at 10:24 pm

    really good points!! thanks for sharing your knowledge

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