Novation KS4 User Manual

Contents

The MixerTo extend the range of sounds that may be reproduced, a typicalAnalogue synthesizer often has more than one Oscillator. By using morethan one Oscillator when creating a sound, it possible to achieve veryinteresting harmonic mixes. It is also possible to slightly detune individualOscillators against each other which creates a very warm ‘fat’ sound.There are has three independent Oscillators and a separate NoiseOscillator.The mixer section is included so that the amplitude (volume level) of eachof these Oscillators and Noise sources may be independently adjustedand mixed together to form a new more harmonically complex waveform.As well as mixing together the individual Oscillators as shown in the dia-gram above, the mixer section allows the relative volume levels of theNoise Oscillator and any external sound source to be set.The FilterThe KS 4 / KS 5 is an Analogue subtractive type of music synthesizer.Subtractive implies that part of the sound is subtracted somewhere in thesynthesis process.The Oscillators provide the raw waveforms with plenty of harmonic con-tent and it is the Filter that subtracts unwanted harmonics in a controllablemanner.Three types of Filter are available. The type of Filter most commonlyfound on synthesizers is the Low Pass type. With a Low Pass Filter, a cut-off point is chosen and any frequencies below that point are passed. Anyfrequencies above are filtered out. The setting of the FREQUENCY knobon the front panel dictates the point below which frequencies areremoved. This process of removing harmonics from the waveforms hasthe effect of changing the sound’s character or timbre. When the FRE-QUENCY knob is set fully clockwise, the filter is set completely open andno frequencies are removed from the raw Oscillator waveforms.In practice, there is a gradual reduction in the volume of the harmonicsabove the cut-off point. How quickly these harmonics are reduced in vol-ume above the cut-off frequency is determined by the Filter’s slope. Thisslope is measured in ‘volume units per octave’. Since Volume is meas-ured in decibels, this slope is quoted in number of decibels per octave(dB). Typical values are 12dB or 24dB per Octave. The higher the num-ber, the faster the harmonics are cut and the more pronounced the filter-ing effect.The button on the sectionl marked SLOPE allows either the 12dB or 24dBtype filter slope to be selected.A further important feature of the Filter is the RESONANCE control.Frequencies at the cut-off point may be increased in volume by this con-trol. This is useful for emphasizing certain harmonics of the sound.As the RESONANCE is increased, a whistling like quality will be intro-duced to the sound passing through the filter. When set to very high lev-els, RESONANCE actually causes the filter to self - oscillate whenever asignal is being passed through it. The resulting whistling tone being pro-duced is actually a pure sine wave, the pitch of which depends on the set-ting of the FREQUENCY knob (the filter’s cut-off point). This resonance-produced sine wave can actually be used for some sounds as an addi-tional sound source if desired.The diagram below shows the response of a typical low pass filter.Frequencies above the cut off point are reduced in volume.SYNTHESIS TUTORIALThe Mixer - The Filter• 11 •OSC 1 OSC 1 VOLUMEOSC 2 VOLUMEOSC 3 VOLUME COMPLEXWAVEFORMMIX OFOSC1, 2 AND 3MIXERINPUT TOFILTEROSC 2OSC 3OSC 1OSC 2OSC 3OSC 1 VOLUMEOSC 2 VOLUMEOSC 3 VOLUMEMIXERINPUT TOFILTERCOMPLEXWAVEFORMMIX OFOSC1, 2 & 3FrequencyVolumeCutoffFrequencyVolumeFrequencyCut offfrequency