Yamaha CS-5 Owner's Manual page 5

number of vibrations, such as 2-fold, 3-fold, and so
on. It is seen that the waveform will gradually come
to resemble a sawtooth waveform. In addition to this,
it is apparent that this sawtooth waveform has a
cycle similar to that of the sine wave that has been
used as the basis. The sine wave with the basic cycle is
referred to as the fundamental and the sine waves of
harmonic overtones as the harmonics. In the case of
musical instruments, the way in which harmonics are
contained in sounds will depend on the arrangement
by which sounds are generated. When we discuss the
difference in tones (waveforms), it is the same as dis¬
cussing what kind of harmonics the sounds contain.
Accordingly, one can express the three elements of
sound in another manner, that is, as 1) pitch, 2) the
manner in which harmonics are contained (harmonic
structure) and 3) volume.
SAWTOOTH WAVE
Fvndtxnicrifab A 2f 3-f 4-f
Ampblute ^
_a. .
3-1- Harmon fes
• STRUCTURE OF THE SYNTHESIZE?)
In the synthesizer, sounds are synthesized by
electronically effecting control on the four properties
of sound (the three elements of sound plus the
envelope), dividing it into 4 blocks.
Control of pitch is effected by the VCO. that of
harmonic spectrum by the VCF. that of volume by
the VCA and that of envelope by the EG (envelope
generator). The following describes the functions of
each block.
• VCO
The VCO block produces sound sources of fre¬
quencies corresponding to the intervals of the key¬
board. The sound source waveforms produced1 by the
VCO are sawtooth waves and square waves that
include many harmonics in a regular manner. These
waves are oscillated, using an electronic circuit.
• VCF
The VCF block determines the tone, changing the
harmonic spectrum of the sound sources by cutting,
or emphasizing, certain parts of the harmonics by
passing the sound sources through filters. The
boundary between the portion that passes through
the filter and the portion that is cut off is known as
the cut-off frequency. The VCF creates the charac¬
teristic harmonic spectrum, by varying the cut-off
frequency.
F: Funda-me/ifa)
In addition to adjusting the cut-off frequency by
means of a knob, the tone is caused to undergo a
temporal change (from the time the sound is
generated to the time it ceases) to give it an "enve¬
lope". This is accomplished by effecting control on
the filter's cut-off frequencies by means of the
envelope generator.
• VCA
The VCA block adds an "envelope" to the volume.
The process starting from the generation of the sound
up to the point the sound gradually fades away is
governed by the envelope generator's ATTACK TIME,
DECAY TIME, SUSTAIN LEVEL, RELEASE TIME
(A.D.S.R.), changing the amplification degree of the
VCA amplifier.
The signals from the VCO reach the VCF where
they undergo a change with regard to their harmonic
spectrum by being passed through a filter. The sig¬
nals, now containing certain tone characteristics, are
given a volume "envelope" at the VCA and then fed
out. In this way, all elements of the properties of
sound are controlled electronically, by utilizing the
three elements of sound and the "envelope." The
synthesizer has, in addition to the blocks described
above, other blocks such as the LFO which permit
further changes in the sounds. But in this case too,
the job is performed by controlling the three ele¬
ments of sound and the envelope.
We hope that the points described in this section
may be helpful to understand the immense possibili¬
ties and great pleasure awaiting you on a path that
will lead you into a new world of music using a
totally new musical instrument, the synthesizer.