Novation X-Station User Manual

Also see for X-Station: Supplementary guide Specifications

Contents

Novation X-Station User Manual Manual pdf 31 page image

The Oscillators And MixerThe Oscillator is really the heartbeat of the Synthesizer. It generates anelectronic wave (which creates the vibrations). This Waveform is pro-duced at a controllable musical pitch, initially determined by the noteplayed on the keyboard or contained in a received MIDI note message.The initial distinctive tone or timbre of the waveform is actually deter-mined by the wave’s shape.Many years ago, pioneers of musical synthesis discovered that just afew distinctive waves contained many of the most useful harmonics formusical synthesis. The names of these waves reflect their actual shapewhen viewed on an instrument known as an Oscilloscope, and areknown as, Sine waves, Square waves, Sawtooth waves, Trianglewaves and Noise Waves.Each one has a specific fixed amount of musically related harmonics(except noise waves) which can be manipulated by further sections ofthe Synthesizer.The diagrams below show how these waveforms look on anOscilloscope and illustrate the relative levels of their harmonics.Remember, it is the relative levels of the various harmonics present in awaveform which determine the tone of the final sound.Sine WavesThese have just a single frequency. This waveform produces the purestsound because it only has this single pitch (frequency).Triangle WavesThese contain only odd harmonics. The volume of each is the square ofits position in the harmonic series. For example, the 5th harmonic has avolume of 1/25th of the fundamental.Sawtooth WavesThese have a rich proportion of harmonics, containing all the harmonicsof the fundamental frequency. The volume of each harmonic is propor-tional to its position in the harmonic series.Square WavesThese only have only the odd harmonics present. These are at the samevolume as the odd harmonics in a sawtooth wave.It will be noticed that the square waveform spends an equal amount oftime in its ‘high’ state and its ‘low’ state. The way in which this definedis known as the ‘duty cycle’. A square wave always has a duty cycle of50% which means it is ‘high’ for 50% of the waveform cycle and ‘low’for the remaining 50% of the waveform cycle.With the KS Synth, it is possible to adjust the duty cycle of the basicsquare waveform to produce a waveform which is more ‘rectangular’ inshape. These are often known as Pulse waveforms. As the waveformbecomes more and more rectangular, more even harmonics are intro-duced and the waveform changes its character, becoming more ‘nasal’sounding.The width of the pulse waveform (often known as ‘Pulse Width’) can bealtered dynamically by a modulator which results in the harmonic con-tent of the waveform constantly changing. This can result in the wave-form having a very ‘fat’ quality when the pulse width is altered at a mod-erate speed.When listening to a pulse wave, it does not make any difference to theperceived sound whether the duty cycle is 40% or 60% since the wave-form has just been inverted and the harmonic content between the twois exactly the same.SYNTHESIS TUTORIALThe Oscillators And Mixer• 31 •VolumeHarmonic1Sine WaveSine Wave HarmonicVolumeVolumeHarmonic1 3 5 7Triaangle WaveTriangle Wave HarmonicVolumeSquare WaveVolumeHarmonic1 2 3 4 5Square Wave HarmonicVolume50%40%10%60%Various duty cycles of rectangular (pulse) wavesSawtooth WaveVolumeHarmonic1 2 3 4 5Sawtooth Wave HarmonicVolume