Crown MARCO-TECH 5000VZ User Manual page 19

Input to the amplifíer ¡s oníy vía P.l.P. module. The standard module
shipped with the MA-5000VZ is the P.I.P.-FXQ. Whether this or any
other module is used, the amplifier senses a balanced input from the
installed module.
Balanced Gain Stage
The Balanced Gain Stage (BGS) amplifier U100A converts the input
audio from a balanced configuration to single-ended with (electrically)
unity gain. The compression device is essentially a shunt across the
balanced input lines. The BGS drives the Variable Gain Stage and
provides information to the compressor control circuit and tothe P.l.P.
connector.
Variable Gain Stage
The Variable Gain Stage (U1 OOB) taps signal from the wiper of the front
panel level control (R120). Gain of the front-end ¡s set by the gain of this
stage. The sensitivity switch (S100, located on the rear panel) selects
the amount of gain ¡n this stage. Overall amplifier sensitivity may be set
for26dB fixed gain (about 5.1Vrms inpuí), 1.4V (+4dBu, unbalanced,
with 8ohmload), or0.775V (OdBu, unbalanced, with 8ohmload). Since
overall amplifier gain afterthis stage is 26dB, íhis stage will have a fixed
gain of OdB (26dB setting), about +12dB (1.4V setting), or about +16dB
(0.775V setting). The output of this stage drives the Error Amp.
Notes
FRONT PANEL
From BGS
R119
8.87K
1
,s>
1
»
A
0
>
6
LEVEL
CONTROL
^ * ^ ¡
S
/
1 R364 .
> 19. 1K ,
>
1
3 I 2 f 1
0 Q- 0 g >
c;i nn i
O l
\J\J
"
^ <0
r- (N
i
R120
5K
\9
0.47
/ • II
\ 1 1
\
' R121
> 49. 9K
i 1
C107
¿ 1OO
35V
R122
49.9K 1
R123
Í
4 ?
C1O8
12
P
F
|(
nr
e r^
^> 7
i
i £- *^x^ U1OOB
•=^- LX> 33078P
To Error Amp
Variable Gain Stage. This is the second
op-amp gain stage in the amplifier. Fea-
tures include front panel level control a
rear panel switch to determine gain of this
stage. Gain of the all other stages is
fixed, therefore changing the gain of this
stage results in a change to overall
amplifier gain. In this case (üke other
Crown amplifiers) the input impedance is
varied to control gain of the op-amp.
MA-5000VZ-17