KEYBOARDS
Kim Bjørn is an author , speaker , electronic musician , and designer with a profound interest in the interactions between people , and between people and machines . Kim lectures , writes , and gives regular talks and workshops on the topics of musical interface design and electronic music instruments . Based in Copenhagen , he now runs his boutique publishing company , Bjooks , while travelling all over the world , as he loves to meet artists , makers , and readers and experience the diverse musical cultures . www . kimbjorn . com .
By Kim Bjørn
Synth Sound Sources From PATCH & TWEAK with Moog
Sound in an analog synth comes in many shapes – waveforms , to
be exact . These are the result of circuits oscillating ( vibrating ) at a steady rate , creating a constant tone . Depending on the waveform , the resulting sound will have more or fewer harmonics , also known as overtones . Let ’ s take a look at these core components of our sound sources .
Harmonics The fundamental – the first harmonic of a sound – is the lowest in frequency and the one we hear as the pitch of the sound . The harmonics are spaced out as integer multiples of the fundamental . The second harmonic vibrates twice as fast , the third harmonic three times as fast , and so on .
The first few harmonics are spaced musically above the fundamental : an octave , an octave and a fifth , two octaves ... The higher they get , the less “ in tune ” they sound ; instead , they add timbral nuances as we don ’ t hear the pitch of these harmonics directly , but instead perceive them as inharmonic elements of the timbre .
Waveforms
Sawtooth The sawtooth ( or saw ) waveform contains both even and odd harmonics , creating a harmonically-rich sound . This makes it ideal for filter modulation and for pad , brass , or string sounds .
Square The square wave only contains the uneven ( odd ) harmonics . It is still a strong sound source , but it ’ s more hollow-sounding than the saw wave and thus well-suited for bass or horn sounds . The square waveform spends equal amounts of time above and below zero volts – a 50 % pulse width .
Triangle The triangle wave is an even less harmonically-rich version of the square wave , containing odd harmonics . Its higher harmonics roll off faster than in the square waveform , and as such , it ’ s great for bass or softer sounds . Filtering a triangle wave removes its upper harmonics , getting it closer to a sine wave .
Sine The sine wave is a pure fundamental with no overtones , so it ’ s less suited for subtractive synthesis , where we filter away harmonic content ; however , it ’ s
great for modulation ( also at audio rate ), sub-bass , drum sounds , etc . You can create a sine wave tone with a self-resonating filter , or with an LFO .
Pulse The pulse wave is an asymmetrical variation of the square wave . The pulse width – the ratio between the positive and negative parts – can be adjusted for a “ buzzier ” sound as the fundamental gets weaker and even harmonics are introduced . Pulse width modulation ( PWM ) can create chorus-like string sounds .
Noise Noise does not have a clear pitch ; it contains a lot of different unrelated frequencies . It ’ s great for adding an organic flavor such as breath or wind to your patches , for percussion sounds , or as a modulation source . Noise is often termed as having a “ colour ” depending on how it is filtered . White noise is not filtered and contains the full frequency spectrum .
Subharmonics While the upper harmonics naturally occur in multiples of the fundamental , subharmonics or undertones are integer divisions of the fundamental . They produce lower notes / frequencies than the fundamental and rarely occur when playing an acoustic instrument , although overbowing a string instrument is one way to produce them .
Subharmonic Synthesis Subharmonics are easier to produce in an electronic instrument , and the German physicist and composer Oskar Sala created his Mixtur-Trautonium electronic instrument in 1948 around this concept . It was used in the soundtrack for Alfred Hitchcock ’ s The Birds . Another such instrument was the East German Subharchord organ from 1958 . The Moog Subharmonicon makes it possible to explore subharmonics , as each of its main oscillators has two subharmonic generators . They each feature 16 subdivisions and can go down to four octaves lower than the main oscillator ’ s pitch . While only a few Eurorack modules exist that make subharmonics directly , you can actually create your own subharmonics with a clock divider .
This column is an excerpt of PATCH & TWEAK with Moog , the ultimate resource for Moog synthesizer enthusiasts and musicians of all skill levels interested in an immersive modular synthesis experience . Get it now at www . bjooks . com .
26 CANADIAN MUSICIAN