Crown MPX-6TM User Manual

@crown

®

 *

System

®

 Product Reference

MPX-6

™

 Mixer-Router

ENABLE

DSPI

L

M

P

+

–

+

–

+

–

+

–

+

–

AUDIO
IN

6

+

–

+

–

+

–

+

–

+

–

MAIN

CROWN      BUS

AUX
CTRL

RS232 / RS422 / PA422

AUDIO
IN

5

AUDIO
IN

4

AUDIO
IN

3

AUDIO
IN

2

AUDIO
IN

1

120 VAC

60 Hz

20 W

SERIAL DATA LOOP

AUDIO
OUT

2

AUDIO
OUT

1

BUS

STACK
IN

MAIN

BUS

STACK
IN

0

-5

-10

-12

5

10

15

21

ADD 25
FOR MIC

L

M

P

0

-5

-10

-12

5

10

15

21

ADD 25
FOR MIC

L

M

P

0

-5

-10

-12

5

10

15

21

ADD 25
FOR MIC

L

M

P

0

-5

-10

-12

5

10

15

21

ADD 25
FOR MIC

L

M

P

0

-5

-10

-12

5

10

15

21

ADD 25
FOR MIC

L

M

P

0

-5

-10

-12

5

10

15

21

ADD 25
FOR MIC

OUT

IN

+ – + –

INPUT

GROUND

ONLY

IN

MPX-6 COMPUTER CONTROLLED MIXER-ROUTER

(Front Panel shown above, Rear Panel shown below)

OVERVIEW

What is an MPX-6?

The MPX-6 is a single rack space five
by one automatic mixer designed to be
configured with a computer and appro-
priate software. Once initially setup the
computer becomes optional. The key to
the MPX-6 operating as a stand alone
mixer is distributed intelligence

™

. In an

IQ System the brains of the system live
out in the system. This means the audio
system is not going to be lost even if the
computer or communication cables fail.
The MPX-6 is an ideal choice for appli-
cations where computerized manual
mixing or routing is desired and the au-
tomation of the SMX-6 or AMB-5 auto-
matic mixers is not required.

HARDWARE BLOCK DIAGRAM

Refer to the pictures of the front and rear
panels shown above and the block dia-
gram of the MPX-6 mixer on Page 2.

Audio Main Inputs:

Six  balanced inputs with removable 3
pin barrier block. The preamp stage in-
cludes:

•  M/L/P switches
set each input to
line level (L) with 0
dB gain, mic level
(M) with 25 dB ad-
ditional gain, or
phantom (P) which is 25 dB addi-
tional gain and +44 VDC phantom
power.
• A trim pot at each input allows for
prefade gain adjustment of –12 dB
to +21 dB gain after the M/L/P
switch.

There are two  VCAs under processor
control at the output of each preamp.
One VCA controls the gain from input to
output mix 1 and the other VCA controls
gain from the input to output mix 2. The
net result is 12VCAs total.

Audio Stack Inputs:

Two inputs, one per output mix. Connec-
tions are via  unbalanced RCA phono
jacks. These inputs are op-amp isolated.
There is no processor control of audio
coming into these inputs. The purpose
of the stack inputs is to allow construc-
tion of a wide mixer with more than six
inputs by taking the outputs of one mixer
and going into the stack inputs of a sec-
ond mixer. This means that main inputs
do not have to be used to expand the
effective size of the overall mixer.

Audio Main Outputs:

There are two summing
buses. Each summing
bus provides the out-
put mix for the corre-
sponding output chan-
nel. Op-amps  buffer
the summing bus to the
output connection and balance the au-
dio output. The outputs are via 3 pin re-
movable barrier blocks.

Audio Bus Outputs:

In addition to the two main outputs, there
are also two bus outputs. Bus outputs 1
and 2 provide the same audio output as
main outputs 1 and 2. Op-amps buffer
the summing bus to the output connec-
tion and balance the audio output. What
makes the Bus Outputs different are re-
lays under processor control which may
be used to turn on or off the Bus Output
drive. 3 Pin removable barrier blocks are
used.

Aux Port:

The unit is equipped with a TB-3M type
mini-XLR port. This port may be used to
provide a control signal or sense a con-
trol signal. Pin 1 is ground reference. Pin
2 is  output under processor control.
When on it provides 10 VDC at 16 ma.
When off it is  open collector (high im-
pedance). Pin 3 is sensing input. +5 to

+30 VDC is sensed as a logic high. The
circuit floats, therefor tie to ground or TTL
source for definite high or low.

Indicators:

A Power light on the front panel indicates
the unit is powered. A DSPI data signal
presence indicator indicates communi-
cation.

Crown Bus Port:

The Crown Bus is a  serial data loop
where components are connected into
the loop and one component serves as
system interface for all. This unit may
serve as a system interface or may sim-
ply operate as a component on a Crown
Bus data loop. Although the Crown Bus
may function on a variety of media,
Crown uses a  two-wire 20 ma current
loop for input and output Crown Bus
connections. On this unit connections
are made via 4 pin removable barrier
block. Even if the unit is communicating
directly with a PC via its serial port, it
always functions in software as an ad-
dressable component on a Crown Bus
loop. The unit must have a valid loop
address. A valid address is:

• 1 to 250 set via 8 segment DIP
switch
• No other MPX on the same Crown
Bus data loop may have the same
address.

The Crown Bus is asynchronous with 8
data bits, 1 start bit, 1 stop bit, no par-
ity, and operates at 38400 baud. The
MPX is not a U-Code protocol compo-
nent.

Serial Port:

The serial port on this unit is a female
25 pin D-Shell.  RS232 and RS422 are
supported with 8 Data bits, 1 start bit, 1
stop bit, no parity. Up to  19200 baud
supported. The serial port for the AMB
may be used for direct communication
with a PC such that the AMB serves as
interface:

+

–

AUDIO
IN

1

L

M

P

0

-5

-10

-12

5

10

15

21

ADD 25
FOR MIC

+

–

+

–

AUDIO
OUT

1

MAIN

BUS

STACK
IN

MPX-6 Mixer (Page 1 of 3)