Yamaha PLG150-AN Bedienungsanleitung Seite 8

Analog Physical Modeling Synthesis and the PLG150-AN Tone Generator
However, the instrument also gives you a wide variety of tools (including Pulse Width Modulation
and Edge) for introducing analog-like "imperfections" to the waveforms and making them much more
complex and interesting.
The VCO of the PLG150-AN actually has two blocks: VCO 1 and VCO 2. With VCO 1, you can
select a variety of waves, and it can be configured with one of three "sync modes" that syncs "master"
and "slave" oscillators within the VCO 1. Thus, when the sync is on, the VCO 1 is actually two oscil-
lators in one, and additional waves are available.
The VCO 1 is always fixed as the FM carrier, but the carrier can either be the master or slave oscillator
depending on the selected algorithm, when Sync mode is set to on. The FM modulator can be
selected from VCO2, the PEG, FEG, LFO1, LFO2 or others. The Pitch Envelope Generator (PEG)
lets you determine how the pitch of the VCO changes over time, and the LFO can be used to modulate
the VCO to create vibrato.
The PLG150-AN also has a second oscillator section: VCO 2. VCO 2 has many of the same waves
and controls as does VCO 1, but differs slightly in the waves that are available . For certain waves, it
also features special cross-modulation that generates complex harmonics by modulating the fre-
quency of the oscillator. The VCO 2 can also be set (with the Sync parameter) to modulate the VCO
1.
Pulse Width and Pulse Width Modulation
In conventional analog synthesizers, pulse width (PW) is used to change the shape of a pulse wave-
form. This changes the harmonics or overtones (which determine the timbre or tone) of the sound.
Pulse width modulation (PWM) uses an LFO to periodically change the width, and hence, the har-
monics.
The PLG150-AN lets you control not only the Pulse wave in this way, but also Saw and Mix (a com-
bination of Saw and Pulse). In addition to using an LFO to modulate the Pulse Width, the PLG150-
AN lets you create a "fat" chorus-like effect, depending on the parameter settings.
Pulse Saw (Sawtooth)
When the Pulse
When Pulse Width is set to When Pulse
Width is small... "64" (50%)... Width is large...
...the sound has ...the sound is that ...the sound has Basic sawtooth When Pulse Width
many harmonics. of typical pulse many harmonics. waveform. is set to a value
wave, with only under "64".
odd-numbered
harmonics.
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