Sony STR-VX4 - Page 30

SONY STR-VX Series Circuit Operation
STK-463 for the STR-VX2) have high
open-loop gain, when negative feedback
is applied, noise and distortion will be
reduced. Figure 3 shows the left
channel main tone amplifier circuit of
the STR-VX1. The simplified version
of this circuit is shown in Figure 4.
The negative feedback loop between
pins 6, 7, and 2 is divided into two
parts. The DC negative feedback is
determined by R609, R608, and C605.
AC negative feedback is determined
POWER AMP BOARD
s6-I
C606
22/16V
Fig. 3.
by all peripheral components. By
changing the amount of AC negative
feedback with the variable resistors
(RV604, RV605), we obtain the de-
sired tone control response. C613
and R616 compensate for flatness at
low frequencies. C606 is connected
to prevent the tone control elements
from affecting the DC negative feed-
back. C604, C609, R607, R613, C607,
C608, R611 and R606 are the periph-
eral elements to make the circuit stable.
R6I7
STR-VX1
Main
Tone
Amplifier
(Left
Channel).
Fig. 4.
Simplified Circuit of Fig. 3.