Yamaha CS2x Anleitung zur Fehlerbehebung PDF herunterladen (Seite 22)

Helper Motors – The LFOs

The Low Frequency Oscillator or LFO is a special kind of oscillator. Unlike VCOs, the LFO’s frequency range

is roughly between 0,1 and 100Hz. Of course the frequencies aren’t used for audio signals, but rather as

controlling signals to modulate the VCO, VCF or VCA sound components. The CS2x calls these LFO modu-

lation types PMOD, FMOD and AMOD.

A synthesizer, just like the human voice, violin, trumpet and many other acoustic instruments, seems “cold”

without the use of some vibrato. To illustrate, select the aforementioned pad sound (TP023): although

enriched by the detuning of its two VCOs it still doesn’t appear as “alive” as would be desirable for a suc-

cessful pad sound. Pitch LFO

to the rescue. This little devil can be used to subtly modulate the pitch of a

sound, thereby making it seem more “alive” – much like the natural vibration of the human voice.

To achieve this effect, use a consistent waveform like the triangle wave. Differing speeds and intensities are

also useful; both VCO’s LFO values should never be identical. It generally pays to offset parameters a little

against each other, not just where LFOs are concerned – this gives synthetic sounds life. Our string pad

(TP033) also gains “depth” from this treatment. In some cases you may even avoid the need for post-chorus-

ing altogether. Any sounds used for solo work should use a slightly delayed Pitch LFO, i.e. Vibrato. This can

best be demonstrated with a simple synthesizer sound (TP034). Here the Material voice used is already pro-

grammed to delay the LFO so that the Vibrato is less abrupt.

Just as much fun can be had with the random Sample&Hold

waveform (TP035). The short melodic phrases

that this waveform can produce have many uses beyond the obvious lead sounds or imaginative sound col-

lages. An LFO with a square waveform can also be used to generate little sequencer-like phrases, such as

fifth or whole octave pitch jumps. Dig deeper in the CS2x’s bag of tricks though and you will find the inge-

nious arpeggiator, which will produce stylish rhythmic musical phrases for you. After all, the overworked LFO

needs a rest now and then!

EXPERIMENT:

You may have stumbled across some sounds in the User bank that at first sound like a simple arpeggiator pattern. A

quick glance to the display however reveals that the Arpeggiator is inactive. Here are the sounds in question “Sq:Cyborg”

and “Fx:SinCrony”. We have modified both of these performances a little – you can find them in the Tutorial Bank

(TP036/037). Your task is to re-activate the LFOs (AMOD and FMOD). You will find that the LFO modulation used in this

sound plays very important role.

Completely different sound impressions can be derived from use of the Filter LFO. Using this sound compo-

nent to control the cutoff frequency of a resonant VCF results in the familiar Wah-Wah effects. The triangle

wave is the obvious waveform to use here. Start out by using a slow LFO speed (TP038) – you can always

tweak it later. An “impulsive” modulation is desirable when quick chord changes are in order, but lingering

pad sounds prefer a more gentle LFO movement. The fun really starts though with the sawtooth waveform,

which will generate rhythmic filter movement just perfect for a sequenced arrangement. The Filter LFO with

the sawtooth wave can also be used to “chop up” filter sweeps (a la TP039). Great fun, and not just for our

young techno generation.

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Yamaha CS2x Anleitung zur Fehlerbehebung Seite 22