Sony STR-VX4 - Page 28

SONY STR-VX Series Circuit Operation
Table
1.
STR-VX
Series
Comparison
Chart
STR-VX6
Output power per channel
PLL
synthe-
sizer
Tuning system PLL
sizer
Memory preset station
Auto tuning level sensor yes
Direct comparator
te
© n
MC phono input
KJ
oO
n
MM load selector yes
Solid-state switch yes
Pulse power supply yes
Heat pipe
Pre-out /main-in terminal
Audio Section
STR-VX1, -VX2, -VX3, -VX4
Phono Equalizer
The entire phono equalizer section in
the STR-VX1 and -VX2 is built around
a high-performance integrated circuit.
The STR-VX3 and -VX4 employ two tran-
sistors in a differential configuration be-
fore the integrated circuit to obtain a
high signal-to-noise ratio (Figure 1).
STR-VX5, -VX6 Phono
Equalizer
The basic circuitry in the STR-VX5 and
-VX6 are identical to the STR-VX3 and
-VX4. However, the STR-VX5 and
-VX6 feature input capability for both
moving-coil (MC) and moving-magnet
type (MM) cartridges (Figure 2). The
MC function is obtained by shorting
R622 with the relay switch S602, and
STR-VX5 | STR-VX4 | STR-VX3 | STR-VX2
[we [uw [ow [aw
synthe-
22 W
PLL Acute Acute Program
synthe- Servo Servo Sensor
sizer Lock
by reducing the input resistance to
100 ohms by S601. When the MC mode
switch is depressed, DC voltage appears
from the control circuit. This voltage
is reduced by R821 and R824 and fed
to the base of Q821 via R823. Then
Q821 turns on to energize relay RY601
to close switches S601 and S602.
The STR-VX6 also features an input
capacitance selector switch (180pF/
330pF) for the MM cartridges by add-
ing R649, C601 and S601-1.
STR-VX1, -VX2 Main Tone
Amplifier
The STR-VX1 and -VX2 do not have
separated tone and power amplifiers.
The STR-VX1 and -VX2 employ a main
amplifier with the tone control circuitry
incorporated in the negative feedback
loop. Because the power integrated
circuits (STK-460 for the STR-VX1;