Ring Modulator - Yamaha CS-50 Servicing Manual

2. RING MODULATOR
This circuit ring-modulates the input signal by use of low frequency modulation signal and takes out the sum and
difference of frequencies for two signals, to make beating.
Input signal
11
+IOV
SPEED lever
vc2
01
MODULATION lever <-.o-----cPUT
r+
Output signal
DEPTH lever
RMO
Control voltag~
generator
(IG00159)
+!OV +!OV
ATTACH DECAY
TIME lever TIME lever
The ring modulation is a sort of amplitude modulation, but it is distinguished from the latter on the basis of
fc;>llowing points. For instance, if the A
3
key (440Hz) is depressed and the ring modulation is made with 10Hz
modulation signal (signal at 7 PIN of ring modulator), the output signal includes the sum and difference of two
signals (450Hz and 430Hz) and does not contain 440Hz input signal, in contrast from the amplitude modulation
of controlling the VCA with the sub-oscillator. That is, though only a key is depressed, two signals of different
frequencies from that depressed key are created. The frequency spectra and the wave shape of these signals are as
illustrated below.
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