6. BASICS OF SYNTHESIS
Your MiniBrute 2S is a true analog synthesizer, so all sounds are produced by analog
electronic circuits. No digital computer circuitry is involved in the generation, filtering, or
basic control of the sound. This is one of the reasons why MiniBrute 2S creates rich,
animated, and lively electronic sounds.
6.1. Analog synthesizer architecture
The analog sound production chain uses a classical approach called subtractive synthesis.
The basic sound generator is a waveform with a rich harmonic content; filtering then
“subtracts” harmonics to create new variations on the original timbre. Subsequent circuits
(an envelope generator in conjunction with a VCA, or voltage-controller amplifier) alter the
level in a precise way to create dynamics.
6.1.1. Signal generators
The signal generators are the circuits that produce the basic waveforms for sound creation.
There are two basic categories: pitched signal generators and the unpitched signal
generators.
6.1.1.1. Pitched signal generator (oscillators)
This device, also called an oscillator, produces an electronic signal characterized by a
repetitive, shaped pattern (called a waveform). The number of times this pattern repeats
in a second determines the signal’s frequency, which determines its pitch. For example, a
pattern that repeats every 2.27ms corresponds to a fundamental frequency of 440 cycles
per second, or 440 Hertz (a unit of measurement for cycles per second named in honor of
Heinrich Hertz, who first demonstrated the existence of magnetic waves, and abbreviated
Hz). This frequency is associated with the pitch of middle A on a piano keyboard. In general,
oscillators will provide some or all of the following basic waveforms: sine wave, triangular
wave, sawtooth wave, square and pulse waves.
If these waveforms have the same frequency, then their pitch is equivalent. However,
different waveform shapes have different timbres. For example, the sine wave sounds dark
and plain, while the sawtooth wave sounds very bright. The square wave sounds a bit like a
clarinet and the pulse wave resembles an oboe.
These complex waveforms are actually made up of multiple sine waves — a fundamental
sine wave that determines the base frequency, and sine waves representing higher
harmonics (also called overtones or partials) of that frequency which, when added together,
produce a unique timbre. These harmonics are an integer multiple of the fundamental
frequency, i.e., the second harmonic is twice the fundamental frequency, the third harmonic
is three times the fundamental, and so on.
A single cycle of each waveform: sine, triangle, sawtooth, square, and
pulse
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Arturia - User Manual MiniBrute 2S - Basics of synthesis
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