10
CIRCUIT DESCRIPTION
1. SURROUND CIRCUIT
This model incorporates a surround processor circuit that provides 6 types of the surround sound. Fig.
1-1
is a block diagram
of the surround processor circuit.
The microprocessor transfers the data to the parameter control ( Serial data, Serial clock, Request Ready ) to operate the
circuits in each mode.
L
A
0608
AK5340
0601
(LC83016E)
PROGRAM
ROM
SUB
ROUTINE
...----.,-------------------------------1
I
INPUT
DATA
I
DE-
:
emphasis
AUTO
INPUT
Balance
Adaptive
MATRIX
Lr.....!:::::;-:;==:;::JF"".'.""I
-------------------
-----------
0603
DRAM
64kx
4bit
C
s
0602
(LC83017JE)
DE-
Correlate
0607
OV06
LC78213
( Block diagram of the surround processor circuit. )
Fig.
1-1
(1) Stereo
Set to this mode to listen to ordinary stereo sound.
The rear L/R and center outputs will be muted.
0706
LC78213
SOURCE
L
OUTPUT
SOURCE
R
OUTPUT
Fig. 1-2
(2) THX Cinema
The
IC
0602
(LC83017E) is a THX Cinema decoder
IC.
IC
0602
(LC83017E) divides the 4 channel signals
(Left, Right, Center and Surround) sourcing from IC
Q601
(LC83016E) into 6 channel signals (Left, Right,
Center,
Surround
Left,
Surround
Right
and
Sub
Woofer).
0601
LC83016E
R
C
s
Fig. 1-3
0602
LC83017JE
>-------+-A
1--------+-C
1-------+-SUBW
t------+s
(3) Dolby pro logic
Q601 (
LC8316E)
is a Dolby pro logic decoder IC.
When an audio signal recorded using the Dolby pro
logic system is sent to this IC, the left, right, center
and surround components are separated. The
surround signal component is delayed by the digital
delay circuit by 15-30
mS
and is sent to the modified
B-type decoder Q601 where noise reduction pro-
cessing is performed.
(4) Movie, 3CH Logic Hall, Matrix
The Movie mode provides the feeling of presence
you get from a 35-mm movie in a movie theater.
3CH Logic mode is used to improve the sound field
center by applying directivity enhancement provided
by the Dolby Pro Logic Surround decoder.
Hall mode provides a sound-field effect of medium-
sized circular hall with rich reverberations.
Matrix mode is effective for playing sports broad-
casts or outdoor live concerts.
It
provides a surround
mode with a wide surround effect.
All the connections of the circuits are the same in
these modes. Q601, controlled by the microproces-
sor, processes the audio signals to produce various
sound effects and creates surround components to
use them as signals to drive the surround channel.
2. CENTER MODE
With Dolby pro logic, three center modes depend on the
use of a center speaker as follows :
NORMAL : Bass frequencies are sent only to the
Left and Right Front channels. Select
this mode when the Center Speaker is
smaller than the Left and Right speakers.
WIDE : Bass frequencies are sent to the Left,
Center and Right speakers. Select this
mode when the Center speaker is
approximately the same size as the Left
and Right speakers.
PHANTOM : Center channel information is sent to the
Left
and
Right
speakers.
Select
this
mode when you do not have a
center
channel speaker.
OV04
LC78212
MASTER
VOLUME
AMP
FRONTL
AMP
FRONT
R
AMP
CENTER
SUB
WOOFER
22
AMP
SURROUND
210
L
9
AMP
SURROUND
100
R
3.
TEST TONE GENERATOR
The test tone generator generates a test tone ( noise ) to
check the balance of sound output from each speaker in
the THX CINEMA MODE, ( This circuit is produced under
license of Lucasfilm Ltd. ) and the Dolby pro
logic mode.
( This circuit is produced under license of the Dolby
Laboratories Licensing Corp. )
0602
LC83017JE
NOISE
GENERATOR
I+---+-
SUBW
( Flow of noise signals within the system. )
Fig. 3
(
C
(·
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