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Subtractive Synthesis: The Beginning

To simplify the search, I have summarized in Table 1.1, for each of the exercises in this chapter, the hardware and software chosen and the sections where you can find them.

Table 1.1. Summary of the different exercises

Before starting, it seems appropriate to clarify that the objective of the exercises, in all chapters, is to learn about subtractive sound synthesis in order to understand it better and master it, but also to allow your ears to discover the sensations and the sounds reproduced by each of the signals that you are going to create. What is the point of doing sound synthesis if not to discover new sounds or understand what it means to reproduce a sound, a timbre, or an already existing tone such as that of a musical instrument or a familiar noise? We need to remember to listen rather than hear, pay attention and discover the richness of the sound universe surrounding us by synthesizing our main constituents.

NOTE.- As the exercises are presented, specific comments will not be repeated to avoid overloading the explanations. In case of doubt or misunderstanding, I advise the reader to go back and read the previous exercises to find the explanatory elements that may be missing.

1.1. Exercise 1 - generate sound with a single oscillator

The basics of sound synthesis are to generate sound from an oscillator. A classic configuration contains an oscillator (VCO) and an amplifier (VCA), which can be preceded by an input controller, often a keyboard.

Figure 1.1. Subtractive sound synthesis with an oscillator. The command signals are represented with dotted lines

1.1.1. Behringer Neutron

The Behringer Neutron semi-modular synthesizer (see Volume 1, section 4.1.3) has two oscillators whose signals can be mixed. For this exercise, we will use Oscillator 1 (Oscillator 2 would have worked the same way, as these two oscillators are identical) and a patch cable, on the matrix, to route it to the VCA. The oscillator has five waveforms, available over three octaves.

Figure 1.2. Exercise 1 for the Behringer Neutron.

Instructions and comments are as follows:

• connect a MIDI keyboard to the MIDI IN input (on the front panel) and switch it on. Check that the keyboard and the Neutron are placed on the same MIDI channel number (1-16). On the Neutron, the adjustment is made with the DIP switches located on the back;
• connect the audio output (OUTPUT) on the back to an amplification system;
• switch on the Neutron;
• connect the output (OUT) of oscillator 1 (OSC1) with a patch cable to the input (IN) of the VCA (VCA IN) on the input-output matrix to the right; this will route the signal produced by the oscillator directly to the amplifier input;
• the controls of oscillator 1 (OSC1) are all accessible. We find the agreement (TUNE), the waveform (SHAPE: mode-tonal, square-pulse, sawtooth, triangle, sinusoid) and the width (WIDTH), which modifies the width of the pulse or the tonal mode when chosen as the waveform and the octave (RANGE - 8', 16' or 32');
• the oscillator mix control knob (OSC MIX) must be turned all the way to the left;
• the VC BIAS button (influence of the VCA) must be turned all the way to the right to open the VCA to the maximum;
• the VOLUME OUTPUT knob can be adjusted to adjust the overall audio output volume to your liking;
• the GATE knob of the LFO must be turned all the way to the left; otherwise, it modifies the signal of the mode-tonal and impulse waveforms;
• all DELAY, OVERDRIVE, ENVELOPE 1 and 2, SAMPLE & HOLD, SLEW RATE LIMITER and ATTENUATORS knobs should be turned all the way to the left.

NOTE.- Instead of connecting a MIDI keyboard, it is possible to use a virtual MIDI keyboard or the one in some DAWs (digital audio workstations). In this case, the connection is made via the USB-MIDI ports of the microcomputer and the Neutron. For the latter, it is located at the back of the device. Again, the MIDI channel numbers must be identical.

1.1.2. Behringer 2600 (ARP 2600)

The Behringer 2600 is one of the ARP 2600 clones (see Volume 1, section 4.1.1) and has similar, if not superior, functionality to today's synthesizers. It is semi-modular but has no separate matrix, and the connection points are distributed on each front panel module.

For this exercise, we will need a patch cable connected to the VCA, the other end of which can be moved to obtain the various signals generated by the oscillator since the equipment does not have a waveform selector.

Oscillator 2 was chosen because it has four waveforms; oscillator 3 would have provided the same results, with these two oscillators being equivalent.

The audio output of the 2600 is stereophonic by default, so you can choose to use both channels or just one. The slide control, PAN, manages the left-right balance.

NOTE.- The names of the commands are not always specified on the serigraphy of the front panel of the ARP 600, Behringer 2600, Korg 2600 or other clones. You can refer to these in the figures for each exercise.

Figure 1.3. Exercise 1 for Behringer 2600 (ARP 2600).

Instructions and comments are as follows:

• connect a MIDI keyboard to the MIDI IN input on the back and switch it on. Check that the keyboard and the 2600 are set to the same MIDI channel number (1-16). On the Behringer 2600, the adjustment is made using the DIP switches on the back. If you are on an ARP 2600, a KORG 2600, or another clone, use the appropriate keyboard;
• connect the one or two audio outputs (L OUTPUT - R OUTPUT) located at the front to an amplification system;
• switch on the 2600;
• connect, using a patch cable, one of the four outputs, TRI, SAW, SINE, or PULSE to input 1 of the VCA;
• the INITIAL OSCILLATOR FREQUENCY, FINE TUNE and PULSE WIDTH controls are active and modify the audio signal. The level 2 control of the MIXER module input controls the output volume. The PULSE WIDTH control, which defines the width of the waveform square, is active if you have chosen the PULSE output of the oscillator;
• the LFO SPEED, VIB DELAY, VIB DEPTH and REVERB controls must be set to zero (lower position of the slider);
• all oscillator 2 input level controls must be set to zero;
• the AUDIO switch of oscillator 2 must be placed on KEYB ON so that the keyboard is active;
• the SYNC switch of oscillator 2 must be set to OFF;
• the INITIAL GAIN control must be placed at its maximum (uppermost position of the slider) to obtain the optimal gain of the VCA;
• the audio signal level control 1 entering the VCA must be placed at its maximum (uppermost position of the slider) to obtain a maximum incoming level;
• the PAN control can be placed in the center position to obtain an audio signal of equal intensity on the right and left outputs.

1.1.3. Max/MSP

The Max/MSP exercises in this book have been tested and designed with version 8.5.4, they may also work on different versions but noticeable differences may occur in some cases1.

You will find in this exercise some of the main Max/MSP functions.

NOTE.- In all Max/MSP exercises, we will not use Live objects2 (Ableton) to allow all users to carry out the work.

Figure 1.4. Exercise 1 with Max/MSP

Instructions and comments are as follows:

• Waveform: radiogroup object outputting 0, 1, 2, 3, or 4 based on user choice (0 for no signal, 1 for sine signal, 2 for sawtooth signal, 3 for triangle signal, 4 for square wave signal);
• notein: MIDI IN acquisition of MIDI notes and information from the keyboard;
• + ; * 12, Octave: allows you to increase or decrease the notes by +/- 2 octaves by multiplying the output of the vertical object radiogroup by 12 and adding it to the...