An1X Tone Generator - Yamaha AN1x Owner's Manual

AN1x Tone Generator

As the AN1x Tone Generator Block Diagram
illustrates, the VCO module generates the basic
signal, then passes it along the signal path to
the MIX/VCF module, which processes the signal
in a variety of ways before passing it on to the
VCA module, which amplifies the signal before
passing it along the signal path to the EFFECT
module comprised of three multi-effects units
and a stereo equalizer, after which the signal is
output from the AN1x's stereo outputs. Along
the way, various real-time and other controllers
can be applied to each module in a variety of
ways.
Oscillators, Filters And Amplifiers
What does it take to make a sound? And how does the
AN1x generate sounds?
In the simplest of terms, there are three basic elements which
make up a sound: pitch, or how low or high it is; tone, or
what its overall quality, or timbre is like; and amplitude, or
how loud the volume level is.
Synthesizers rely on three key electronic components to generate
sounds and electronically imitate the soundwaves of familiar musical
instruments, as well as create entirely unique sounds. In traditional
analog synthesis, the source sound pitch is generated by an
oscillator; its tone is created by a filter; and its volume is determined
by an amplifier. With the AN1x, these three elements are termed
the VCO (voltage controlled oscillator), the VCF (voltage controlled
filter), and the VCA (voltage controlled amplifier).
VCO VCF
The filter determines the timbre
The oscillator creates the source pitch
The "signal path" starts at the VCO, flows to the VCF, then
flows to the VCA. The signal is "processed" at each block, or
"module" along the way to the final output.
VCA OUT
The amplifier determines
the volume
1 VCO
The VCO module is where the original sound waveform gets
generated. Although a single oscillator is enough to generate
the basic sawtooth, pulse (square) or other waves required
for different types of musical instrument sounds, the AN1x's
VCO module is much more complex.
First, there's a VCO1 which includes an additional saw2 and
mix wave, and which can be configured with one of three
"sync algorithms" that syncs "master" and "slave" oscillators
within the VCO1, and can be modulated by FM according to
the algorithm. Thus, when the sync is on, the VCO1 is
actually two oscillators in one, and three additional "inner"
waves are available.
The VCO1 is always fixed as the FM carrier, but the carrier
can either be the master or slave oscillator depending on the
selected algorithm. The FM modulator can be selected from a
second VCO (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.
For more information, see as follows:
VCO1 — page 61
VCO2 — page 63
SYNC/FM — page 58
PEG/LFO — page 54
2 MIX/VCF
The MIX/VCF module is where the mixing of VCO1,
VCO2, Ring Modulator, Noise and Feedback signals
take place, which can then be filtered by the VCF High
Pass Filter (HPF), Low Pass Filter (LPF), Band Pass Filter
(BPF) and Band Eliminate Filter (BEF). You can
determine the cutoff frequency of the VCF, as well as
amount of Resonance, or emphasis around the
frequency cutoff point. The Filter Envelope Generator
(FEG) lets you determine how the timbre of the signal
changes over time, and the LFO1 can be used to
modulate the VCF to create wah.
For more information, see as follows:
MIX/VCF — page 66
VCF — page 64
HPF — page 67
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