Creating a Filter in Pure Data
Learn Synthesis with Pure Data S01E08 -Creating a Filter in Pure Data
In this episode, we will take a look at an approach called subtractive synthesis. This approach is usually performed by filtering the frequency spectrum. We will see how to make a band pass filter and a low pass filter that has center and cut off frequency controls as well as Q controls. This will allow us to ass a simple filter to our synthesizer and shape the frequency spectrum better.
The use of filters is the primary way of utilizing the approach of subtractive synthesis. This is an approach in synthesis in which complex harmonic content is filtered, whereby different types of filters are used to pass and attenuate certain ranges of frequencies depending on the type of filter used. Subtractive synthesis is a major part of almost all sound design forms even beyond synthesis. In this video, one will learn how to use a filter in Pure Data to provide band pass filtering as well as low pass filtering. The video also shows how one can apply the common parameters that are associated with these filters. One will see how to control the cut off and center frequency setting as well as the Q or bandwidth parameter. As an addition tot he core of the subject matter, the video also shows how to apply the general MIDI controller signal, such as modulation wheel to control these parameters of the filter.
As always, we integrate this filter into the synthesizer that we are developing in Pure Data. The video shows how to place this new module into the signal flow of the rest of the synthesizer. This filter is best used with the waveforms that actually have harmonic content, such as the triangle wave, square wave, and sawtooth wave. Since the sine wave does not have harmonics, it is not a wave shapes that can be used in subtractive synthesis.
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