Sony STR-VX4 - Page 31

SONY
STR-VX
Series
Circuit
Operation
STR-VX3 Tone Amplifier
Like
the
STR-VX1
and
-VX2,
the
whole
control
circuitry
is
built
around
the
operational
amplifier
NJM4560D
(1IC601,
Figure
5),
which
is
connected
in
a
non-
inverting
configuration
with
bass
and
treble
controls
incorporated
in
the
nega-
tive
feedback
loop.
The
STR-VX3
fea-
tures
a
subsonic
filter
that
cuts
the
S5-1 REA __s6-1
LOUDNESS SUBSONIC
OFF—+ON OFF—=ON
C603 C604
0.082 0.033
noise
by
12
dB
per
octave
below
15
Hz.
This
is
to
eliminate
such
very
low
fre-
quency
noise
as
the
rumble
produced
by
phono
records.
Figure
6
shows
the
simplified
subsonic
filter
circuit
of
the
STR-VX3.
When
the
subsonic
filter
switch
(S6-1)
is
depressed,
the
circuit
operates
as
a
two-stage
high-pass
filter
(Figure
6b).
Fig.
5.
STR-VX3
Tone
Amplifier
(Left
Channel).
4 C603 cé604
(b)
Fig.
6.
STR-VX3
Simplified
Subsonic
Filter
Circuit.