programming with max/msp - Virtual Sound

Chapter 3P - Noise generators, filters, and subtractive synthesis
3.1 SOUND SOURCES FOR SUBTRACTIVE SYNTHESIS
As you learned in Section 3.1T, the purpose of a filter is to modify the spectrum
of a signal in some manner. In this section, before introducing filtering in
Max/MSP, we will introduce an object that you can use to display a spectrum:
the spectroscope~ object. This graphical object can be found near the end
of the palette, in the vicinity of the scope~ object (as shown in Figure 3.1). As
usual, if you can’t find it in the palette, create an object box and type the name
“spectroscope~” into it.
Fig. 3.1 The spectroscope~ object
Open the file 03_01_spectroscope.maxpat (shown in Figure 3.2).
Fig. 3.2 The file 03_01_spectroscope.maxpat
In this patch, we have connected a selector~ object to the spectroscope
so that we can switch between three oscillators, one generating a sine wave
(cycle~), one generating a non-band-limited sawtooth wave (phasor~), and
one generating a band-limited sawtooth wave 1 (saw~). The three message
boxes connected to the left input of the selector~ object are used to pick
one of the three oscillators; by setting the frequency in the float number box
and then moving between the three oscillators, you can compare their spectra.
Observe that the sine wave has only one component, while the phasor~,
being a non-band-limited object, has a much richer spectrum. 2
1 See Section 1.2.
2 The spectroscope~ object uses an algorithm for spectral analysis called the Fast Fourier
Transform. We already mentioned the Fourier theorem at the end of Chapter 2T, and we will return
to a much more detailed discussion of it in Chapter 12.
from “Electronic Music and Sound Design” Vol. 1 by Alessandro Cipriani and Maurizio Giri
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