571
15
Block Diagram
Figure 7-2 is the block diagram for the 571. Please take a moment and take note of the following:
All signal inputs and outputs are balanced transformerless.
The line inputs, H
OUSE
P
AGE
I
N
and M
USIC
I
N
, are unity gain.
The mic inputs (PAGE MIC and SENSE MIC) have up to 48 dB of gain. They are equipped with
15V phantom power for condenser mics.
All of the trimpots (page mic and sense) have stop resistors at the CCW end of their rotation
which prevents them from attenuating to infinity. The range is limited to -26 dB for the P
AGE
M
IC
trimpot, and -40dB for the S
ENSE
1 and S
ENSE
2 trimpots.
Signals on either page input operate the ducker. The ducker attenuates music signals whenever
there are signals present on either page input. The P
AGE
O
VER
M
USIC
control determines the
amount of ducker action.
The format switch defeats the music input and selects the source for the 571s program level
detector.
Using the remote O
UTPUT
G
AIN
T
RIM
control defeats the front-panel mounted control.
Different grounding options are possible via TB2-6 and TB2-7.
The microprocessor runs the show.
Figure 7-2. 571 block diagram.
S
S
E
R
P
PRESS
R
P
S
S
E
1
4
2
5
3
6
HOUSE
PAGE
IN
PAGE
MIC
PAGE
MIC
TRIM
SENSE 1
TRIM
SENSE 2
TRIM
SENSE
MIC 1
SENSE
MIC 2
MICROPROCESSOR
LEVEL
DECTECTOR
LEVEL
DECTECTOR
DUCKER
SIDECHAIN
MULTIPLEXER AND
A/D CONVERTER
OUTPUT
GAIN TRIM
MAX
LEVEL
AVERAGING
TIME
PAGE OVER
MUSIC
FORMAT
MUSIC
MUSIC
PAGE
PAGE
RATIO
D/A
CONVERTER
MEMORY
DISPLAY
MUSIC
IN
VCA
CHASSIS GROUND
AUDIO
OUTPUT
CIRCUIT GROUND
TB2
10ohm
.01mFd
TB2
TB1
JP1
B
7 Vc
A
TB1
TB1
TB1
7
1
2
3
4
5
9
10
6
8
VOLTAGE
REFERENCE
