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C l e a r l y   b e t t e r   s o u n d

Cloud Electronics Limited

140 Staniforth Road, Sheffield, S9 3HF. England. Telephone: +44 (0)114 244 7051 Fax: +44 (0)114 242 5462 Web: www.cloud.co.uk Email: info@cloud.co.uk

The  Cloud  CX-A450  and  CX-A850  are  high-quality  multi-

channel power amplifiers designed for relatively low-power sound 
reinforcement  applications  in  commercial  or  industrial  premises. 

They  are  ideal  for  situations  where  the  various  locations  of  the 
building require different programme material and/or levels.

The two models are:

MODEL

POWER 

CX-A450

4 x 50 W

CX-A850

8 x 50 W

The amplifiers will deliver their rated power into 4 ohm loads for 
long periods of time. Safety features of the design include Cloud’s 
Dynamic  Clipping  Protection  circuitry, VI  limiting,  switch-on  delay    
(5 seconds) and protection against DC offset or thermal overload. 
Both  models  are  built  in  a  2U  steel  enclosure,  and  use  variable–
speed forced-air cooling.

Any  two  channels  may  be  wired  in  Bridge  Mode,  allowing  power 
outputs  of  double  the  normal  rating  to  be  delivered  to  a  load  of        
8 ohms (minimum).

In addition to the power switch and associated LED, the front panel is 

fitted with three LEDs for each channel, confirming signal presence, 
peak  level  and  activation  of  the  protection  circuitry.  Rear  panel 

controls  are  provided  for  individual  channel  gain  trims  and  input 
routing to configure the amplifier in various combinations of mono, 
stereo  or  multi-channel  operation.  The  inputs  are  electronically 
balanced.

The CX-A450 and CX-A850 may also be used with 100 V/70 V-line 
loudspeaker systems by the addition of standard Cloud accessories. 
The  CXL-4160  is  a  four  channel  transformer  module  which  can 
be internally fitted to the CX-A450, while the CXL-40T is a single 
channel  toroidal  transformer  module  for  external  mounting.  For 

installation convenience, the CXL-800, a 2U rackmounting assembly 
which can hold up to eight CXL-40s, is also available. To prevent LF 
transformer saturation in 100 V/70 V-line systems, a 65 Hz high-pass 
filter may be enabled for each channel individually, by internal jumper.

Other  standard  options  are  Cloud  RL-1  remote  volume  control 
plates,  the  VCA-5  single-channel  VCA  card  (required  for  level 
control by RL-1), and EQ cards to suit various makes and models of 

loudspeakers. Remote level control or speaker EQ may be fitted to 
any or all channels.

Cloud CX-A450 - front panel view

Cloud CX-A850 - front panel view

CX-A450

FOUR CHANNEL POWER  AMPLIFIER

PROTECT

PEAK

SIGNAL

POWER

4

3

2

1

EIGHT CHANNEL POWER AMPLIFIER

CX-A

850

1

2

3

4

5

6

7

8

PROTECT

PEAK

SIGNAL

POWER

CH 1

REMOTE

LEVEL

1

2

3

RL-1

1

2

3

CH 2

REMOTE

LEVEL

RL-1

2

1

3

3

2

1

CH 3

REMOTE

LEVEL

RL-1

2

1

3

3

2

1

CH 4

REMOTE

LEVEL

RL-1

2

1

3

3

2

1

1

3

2

1

LEVEL

2

3

2

1

LEVEL

3

3

2

1

LEVEL

4

3

2

1

LEVEL

POWER INPUT

FUSE

REPLACE FUSE

WITH SAME TYPE

AND RATING

230V  -  3.15A  H

115V  -  6.3A  H

THIS  PRODUCT  MUST  BE  EARTHED

40-60Hz

5%

V

SPEAKER  OUTPUTS

MINIMUM LOAD 4OHMS

OUTPUT  RATING  50W/4OHMS

100V/70V  LINE

OUTPUTS

CH1

CH2

CH3

CH4

1

2

1

2

3

4

(OUT)

(IN)

(IN)

(OUT)

(IN)

(OUT)

CH1

0V

0V

CH2

0V

CH3

0V

CH4

SOURCE

SOURCE

SOURCE

HIGH VOLTAGE

THIS COVER

REMOVE

DO NOT

OUTPUT

DANGER

LINE

100V/70V

REMOTE

LEVEL

REMOTE

LEVEL

REMOTE

LEVEL

REMOTE

LEVEL

REMOTE

LEVEL

REMOTE

LEVEL

REMOTE

LEVEL

REMOTE

LEVEL

FUSE

230V  -  T4A

115V  -  T8A

CH 1

RL-1

1

2

3

1

2

3

1

2

3

RL-1

2

3

1

1

2

3

RL-1

2

3

1

1

2

3

RL-1

2

3

1

1

2

3

RL-1

2

3

1

1

2

3

RL-1

2

3

1

1

2

3

RL-1

2

3

1

1

2

3

RL-1

2

3

1

CH

CH

CH

CH

CH

CH

CH

2

3

4

5

6

7

8

1

2

1 2 3

LEVEL

SOURCE

- --

2

(OUT)

(IN)

(OUT)

1

(IN)

3

3

SOURCE

LEVEL

1 2 3

--

-

(OUT)

2

(IN)

4

4

SOURCE

LEVEL

1 2 3

--

-

(OUT)

1

(IN)

5

5

SOURCE

LEVEL

1 2 3

--

-

(OUT)

2

(IN)

6

6

SOURCE

LEVEL

1 2 3

--

-

(OUT)

1

(IN)

7

7

SOURCE

LEVEL

1 2 3

--

-

(OUT)

2

(IN)

8

8

SOURCE

LEVEL

1 2 3

--

-

LEVEL

1 2 3

--

-

1

SPEAKER OUTPUTS

OUTPUT RATING  50W / 4OHMS

MIN LOAD 4 OHMS

0V

CH1

0V

CH2

0V

CH3

0V

CH4

0V

CH5

0V

CH6

0V

CH7

0V

CH8

POWER INPUT

REPLACE FUSE WITH SAME

TYPE AND RATING

THIS UNIT MUST BE EARTHED

5%

40-60Hz

CLOUD  MULTI-CHANNEL POWER AMPLIFIERS

MODELS CX-A450 & CX-A850

Cloud CX-A450 - rear panel view

Cloud CX-A850 - rear panel view

General Description

Summary of Contents for CX-A450

Page 1: ...lso available To prevent LF transformer saturation in 100V 70V line systems a 65 Hz high pass filter may be enabled for each channel individually by internal jumper Other standard options are Cloud RL 1 remote volume control plates the VCA 5 single channel VCA card required for level control by RL 1 and EQ cards to suit various makes and models of loudspeakers Remote level control or speaker EQ ma...

Page 2: ...ion Pairs of channels may be operated in Bridge Mode Per channel front panel LEDs for signal presence peak level and protection status Balanced line level inputs with gain trim Rear panel switches to configure for multichannel stereo or mono operation Optional internal 4 channel 100 V 70 V transformer module CX A450 only Optional externally mountable 100 V 70 V transformers per channel Optional re...

Page 3: ...e r s o u n d Input Routing The input routing switches of the CX A450 and CX A850 permit various permutations of mono stereo and multi channel operation without any external parallel wiring Some possibilities are shown below ...

Page 4: ...d to various zones parts of a building They are equally suitable in a situation where a common audio source needs to be reproduced at different levels in various zones The flexibility of the amplifiers input routing makes it possible to handle a mixture of mono and stereo sources without complex wiring In many applications the power amplifiers will be used in combination with a Cloud Zoner to perm...

Page 5: ...p Trace Line Style Thick Data Axis Comment 1 1 Red Solid 1 Anlr Bandpass Left CH2 to CH1 100 0 80 60 40 20 d B r 20 20k 50 100 200 500 1k 2k 5k 10k Hz T T Audio Precision 05 31 11 13 23 50 CX A850 Crosstalk Color Sweep Trace Line Style Thick Data Axis Comment 1 1 Red Solid 1 Anlr Bandpass Left 100 0 80 60 40 20 d B r 20 20k 50 100 200 500 1k 2k 5k 10k Hz T Audio Precision 05 31 11 13 11 59 CX A450...

Page 6: ...stalk 70 dB rel rated output into 4 ohms 10 kHz 82 dB rel rated output into 4 ohms 10 kHz VCA module THD N 0 03 1 kHz 22 Hz 80 kHz BW Inputs Type connectors Electronically balanced 3 pin 3 5 mm pitch screw terminal connectors Sensitivity 0 dBu 0 775Vrms Input Impedance 10 kohms balanced General Output Connectors lo Z 2 pin 5 mm pitch screw terminal connectors Output Connectors 100 70 V Screw termi...

Page 7: ...ency of 65 Hz independently in each amplifier channel Each channel shall deliver its rated power from an input signal of 0 dBu with input level controls set at maximum Output mute protection on power up and thermal protection shall be provided The amplifiers will also be protected against short circuits at the output and excessive combination of output voltage and current The amplifiers outputs sh...

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