Novation X-Station User Manual

Also see for X-Station: Supplementary guide Specifications

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Novation X-Station User Manual Manual pdf 30 page image

It is recommended that this chapter is read carefully if Analogue soundsynthesis is an unfamiliar subject. Users familiar with this subject canskip this chapter and move on to the chapter - The KS Synthesizer onPage 34.Elements of a soundTo gain an understanding of how a Synthesizer generates sound it ishelpful to have an understanding of the components that make up asound, be it musical or non musical.The only way that a sound may be detected is by air vibrating theeardrum in a regular, periodic manner. The brain interprets these vibra-tions (very accurately) into one of an infinite number of different types ofsound.Remarkably, any sound may be described by just three terms, and allsounds always have them. They are :* Volume* Pitch* ToneWhat makes one sound different to another is the proportion of thesethree qualities initially present in the sound and how these three termschange throughout the duration of the sound.With a musical synthesizer, we deliberately set out to have precise con-trol over these three terms and, in particular, how they can be changedthroughout the duration of the sound. These terms are often given dif-ferent names, Volume is referred to as Amplitude, Pitch as Frequencyand Tone as Timbre.PitchTaking the example of air vibrating the ear drum, the pitch is determinedby how fast the vibrations are. For an adult human, the lowest vibrationperceived as sound is about twenty times a second, which the braininterprets as a bass type sound, and the highest is many thousands oftimes a second, which the brain interprets as an extreme treble typesound.If the number of peaks in the two waveforms (vibrations) are counted, itwill be seen that there are exactly twice as many peaks in Wave B as inWave A. (Wave B is actually an octave higher in pitch than Wave A). Itis the number of vibrations in a given period that determines the pitch ofa sound. This is the reason that pitch is sometimes referred to as fre-quency. It is the frequency of the waveform peaks which are countedduring a given period of time.ToneMusical sounds consist of several different related pitches occurringsimultaneously. The loudest is referred to as the ‘Fundamental’ pitchand corresponds to the perceived note of the sound. Pitches related tothe fundamental are called harmonics. The relative loudness of theseharmonics compared to the loudness of all the other harmonics (includ-ing the fundamental) determines the tone or ‘Timbre’ of the sound.Consider two instruments such as a harpsichord and a piano playingthe same note on the keyboard and at equal volume. Despite havingthe same volume and pitch, the instruments would still sound distinctlydifferent. This is because the harmonics present in a piano sound aredifferent to those found in a harpsichord sound.VolumeVolume, which is referred to as the amplitude or loudness of the soundis determined by how large the vibrations are. Very simply, listening to apiano from a metre away would sound louder than if it were fifty metresaway.Having shown that just three elements make up any sound, these ele-ments now have to be related to a Musical synthesizer. It is logical thata different section of the Synthesizer ‘Synthesizes’ (or creates) thesedifferent elements.One section of the synthesizer, the Oscillators provide raw waveformswhich provide the pitch of the sound along with its raw harmonic con-tent (tone). These signals are then mixed together into a section calledthe Mixer and the mixed oscillator signal is then fed into a sectionnamed the Filter which is responsible for further altering the tone of thesound. It does this by removing (filtering) certain undesired harmonicfrequencies. Lastly, the filtered signal is fed into a final section, theAmplifier which determines the final volume of the sound.Additional synthesizer sections; LFOs and Envelopes provide ways ofaltering the pitch, tone and volume of a sound by interacting with theOscillators, Filter and Amplifier, providing changes in the character ofthe sound which can evolve over time. Because LFOs and Envelopesonly purpose is to control (modulate) the other synthesizer sections,they are commonly known as ‘modulators’.These various synthesizer sections will now be covered in more detail.SYNTHESIS TUTORIALElements Of A Sound• 30 •Wave BWave AWave B is twice the pitch of Wave ATimeWave BWave AVolumeWave A is louder than Wave B but is the same pitchOscillators Mixer Filter AmplifierAudio path of the main Synthesizer blocks