3 input sensitivity adjustment, 4 additional load protection, Eration, distortion and excessive heating – Crown Audio CSL Series User Manual

Page 8: Csl series power amplifiers page 8, Fig. 2.4 loudspeaker fuse nomograph

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CSL Series Power Amplifiers

Page 8

eration, distortion and excessive heating.

2.3 Input Sensitivity Adjustment

The input sensitivity switch inside the amplifier is set to
0.775 volts at the factory. It can be changed to 1.4 volts
or a voltage gain of 26 dB as follows:

1. Turn off and unplug the amplifier from the AC source.

2. Remove the access cover on the back panel.

3. Locate the labeled access hole for the sensitivity switch.

4. Set the switch to the desired position.

5. Replace the access cover plate.

When set to 26 dB gain, the

460 CSL requires a 2.0 volt

input, the

800 CSL requires a 2.5 volt input and the 1400

CSL requires a 3.2 volt input to deliver full output into an
8 ohm load.

2.4 Additional Load Protection

Because

CSL amplifiers can generate enormous

power, it may be desirable to protect loudspeakers from
damage due to excessive power. A common way to do
this is to put a fuse in series with the load. This may be
accomplished with a single fuse to protect the entire
system, or by fusing each driver separately. Use Figure
2.4 to find the correct fuse.

Example: (A) Choose the peak music power for the loudspeaker
(such as 75 watts). (B) Find the loudspeaker impedance (8
ohms). (C) Draw a line between points A and B. The line inter-
sects the middle scale at the correct fuse value (1.5 amps).

Fig. 2.4 Loudspeaker Fuse Nomograph

1.0

1.2

1.4

1.6

2.5

3

4

5

6

7

8

9

10

12

14

16

20

25

30

20

15

10

8

6

5

4

3

2

1.5

1

.8

.6

.5

.4

.3

.2

.15

.1

.08

3000

2000

1500

1000

800

600

400

300

200

150

100

80

60

40

30

20

15

10

8

6

4

3

2

1.5

1

SPEAKER Z

(ohms)

FUSE

(amps)

SPEAKER RATING

PEAK MUSIC POWER

(watts)

(Typically 4 times the continuous average power)

Example: Z = 8 ohms.

Peak Power = 75 W

Answer: Fuse = 1.5 A

2

40

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